(Provided the yeshiva students are from an Orthodox background).
Rabbi Burg, the national director of NCSY, writes in the JTA that,

Thousands of Orthodox students will soon head off for their post-high school year of study at a yeshiva in Israel.
What about those public school students who you send to yeshiva who are not completely Orthodox?
Judging from recent years, many of them will contract what is derisively referred to as Flipping Out Syndrome, or FOS, a troubling malady that pits teenager against parent in a seemingly endless cycle of friction and misjudgment.

Rabbi Burg writes about this phenomenon as if NCSY is against this. In fact, NCSY encourages such behavior even domestically, and has for years. NCSY has long promoted increased religious observance as a form of rebellion.
As Michael Kress wrote in Salon back in 2000,

At a typical NCSY Shabbaton (weekend retreat), the Havdala (a ceremony ending Shabbat) always loomed large. A short celebration involving a multiwicked candle, wine and a spice box, Havdala is usually a quick affair. But at NCSY events, leaders would pass around the candle, asking kids to say something meaningful when the candle was passed to them. The kids’ stories generally involved nonobservant youth who became observant, thanks to the NCSY. And inevitably, those teens and preteens would elaborate on the sacrifices they made for their faith: enduring hostility from their parents; refusing to eat at their parents’ not-kosher-enough home; refusing to spend weekends at their non-Shabbat-observant home.
As disturbing as these narratives might have seemed (they certainly bothered me), the NCSY encouraged them. The organization openly disregarded parental concerns and prided itself on the courage of children who could make a complete lifestyle change overnight — the consequences be damned.

Note that Kress’s primary concern is not already Modern Orthodox Jews who become more religious, but rather, secular/liberal Jews who become Orthodox.
Yet Rabbi Burg does not address those concerns at all, even though he is writing for the JTA, a newswire that services community Jewish newspapers nationally, and those newspapers service a predominantly liberal and secular Jewish readership. But strangely, Rabbi Burg restricts the conflicts to those between already Modern Orthodox Jews and their Orthodox parents.
Let us be clear. The conflicts engendered by NCSY’s recruitment of liberal and secular Jews to haredi baal teshuvah yeshivas – which until recently, were all but the only yeshivas they sent such Jews to, never mind the dominant ones – is hardly limited to a disagreement over a specific vitamin’s kashrut acceptability. In fact, such issues may of very minor concern for most secular Jews overall compared to the larger ones they face.
But what Rabbi Burg did not address is the larger issues facing liberal and secular Jewish parents and their high school graduate teens.
The conflicts created from teens adopting the ideologies of the haredi institutions NCSY guides them to include (but are not limited to): A rejection of scientific method, in accordance with the haredi leaders they report to; a postponement of college indefinitely; a rejection of secular education as a worthy goal in itself; a rejection of full-time secular college; a preference for maximum halachic (Jewish Law) compliance (hardly restricted to kashrut); acceptance of stringencies not recognized as halacha outside of the ultra-Orthodox; anti-Americanism; encouragement of restrictive haredi garb; a rejection of friends and even family members who aren’t Orthodox; a contempt for Modern Orthodoxy; a belief that haredi leaders are near-infallible, an acceptance of inferior status within the ultra-Orthodox because of their niddah conception and non-Orthodox background.
It is unfortunate that Rabbi Burg did not address these concerns of secular and liberal Jewish parents. He is certainly aware of them. NCSY and the Orthodox Union have taken tremendous pride in recruiting their children to haredi yeshivas and seminaries. And NCSY has expanded the public school population they serve tremendously. They control over 170 clubs in our public schools. Rabbi Burg is the “dean” of the Jewish “Student” Union.
But perhaps that isn’t the point. Those parental concerns aren’t really any more valid now than they ever were for NCSY. Because they aren’t Orthodox.
At least Modern Orthodox Jewish parents have some leverage over NCSY. After all, the parent organization is the Orthodox Union, a right-wing Modern Orthodox organization, even if its youth group leans haredi. NCSY has been careful to offer already Modern Orthodox teens Modern Orthodox options because Modern Orthodox parents insisted on that.
But secular and liberal Jewish parents have no representation, and no voice. Additionally, they usually do not understand the difference between Modern Orthodoxy and ultra-Orthodoxy. Jewish parents think it is their kid, their kid’s specific baal teshuvah yeshiva/seminary, their kid’s specific rabbi.
NCSY has taken advantage of their naivety and trust consistently and effectively. The concerns come after the fact, not before. They don’t require addressing. At that point, NCSY already got what they wanted.
Even in this attempt to appear moderate in a Jewish newswire that primarily services secular and liberal Jewry, NCSY’s leader utterly ignores the concerns of secular and liberal Jewry.
Excuse me for feigning shock and surprise.
Earlier: Is NCSY appropriate for our public schools?