It absolutely is either loshon hora, or, more likely, motzi shem ra.
Most Litvishe gedolim in America recognized the need for a secular studies program for mesivta aged boys, and even those who are against it would agree that if there is one, it must be a serious program.
The Litvishe gedolim only recognize the “need” for the secular studies as a b’dieved because the government requires it and if they didn’t offer it many parents would not send their children to a good yeshiva (with no secular studies). L’chatchcila they would agree that it would be better to have no secular studies and have longer Limudei Torah.
But there is nothing intrinsically good about a secular program, even according to the gedolim who allow it and have it for the above reasons. So, no, there is no loshon hora or msr whatsoever in being dismissive of it.