The relevant text of the law is
The products must be available to all menstruating students in restrooms regularly used by students in grades 4 to 12 according to a plan developed by the school district.
so, I think "boys bathroom" only in the case where a school has trans-boy without puberty blockers or hormone therapy. Clearly a very edge case, but right-wing propaganda depends on blowing up rare events or special circumstances, pretending they're happening everywhere, all the time, and therefore an immediate threat to the way their audience has always done things.