It's controversial because if the rest of the all girls Catholic school Chanda attends knew Brock was in the same body, the nuns would throw a fit...and probably some of the parents as well. I mean this is the South Western United States we're talking about.

Chanda and Brock's parents know about their condition but they wanted their child(ren) to have a good non-public school education. Their parents want them to avoid the perils of Public School in Valencia County. They figured a Catholic school was the best bet, however most Catholic schools are either boys only or girls only. The protag's secret can't be leaked.