TLIK, children with televisions in their home affects the child and carries a very strong possibility of that child negatively affecting classmates. No question about it. And there are other influences that a child can have that will negatively affect his or her classmates that must be accounted for. Sometimes the damage that can be done to multiple classmates is more than the damage of requiring that one child to change yeshivas.
You cannot state there are no situations where a child must be required to switch to another yeshiva. And with the extremely limited information presented and potentially biased author, no one can state whether the case in the OP or other cited cases in this thread were indeed justified or not. (It certainly can also have been unjustified.)