This part does not seem to be true.
The same boy was accused of raping a girl in a bathroom at Stone Bridge High School on May 28 and then of raping another girl in a classroom at Broad Run High School on October 6. Both schools are part of the Loudoun County Public Schools.
On August 10 (between those two incidents), the school board adopted a policy to allow transgender students to use the bathroom that corresponds with their gender identity.
1. The transgender-inclusive bathroom policy was not yet in place when the boy entered the girls' bathroom on May 28. Also, to the superintendent's knowledge, this accused rapist is not a transgender girl. Thus, no one had "allowed" the boy to use the girls' restroom.
2. The transgender-inclusive bathroom policy was in place when the boy raped again, but since that second rape happened in a classroom and not in a bathroom, any bathroom policy is N/A for describing the incident.
Sources:
https://loudounnow.com/2021/10/22/board-members-were-informed-day-of-alleged-stone-bridge-assault/