If they receive public funds, they may be required by law to block access to porn sites (as some public libraries are)... and as such they just set their filter to "high" (figuratively speaking) and just have it over-zealously block anything that sounds like it might be sexually oriented (probably blocks access to some sites with breast cancer research, for example.) Among other things, they probably use a blacklist/whitelist provided by a third party that blocks anything referencing crossdressing (and the folks who make those lists, most if not all being your typical John Q. Cisgender, just assume anything related to crossdressing is porn.)
One can jump to conclusions about some sort of discrimination, but seriously, it is almost certainly just an overaggressive filter they are using, and they probably have no idea that non-porn TV/TS sites are blocked (if they even know such things exist to begin with.)
One can always try using a proxy, it might work. After all, it is what teenagers do to access naughty sites when they are on a connection with a filter.