The simple solution has several elements.
1) For those athletes that require scholarships, take up a collection of money to replace it.
2) Most of the team and their parents boycott the team.
3) Hold “alternative” swim meets in private facilities, with no genetic males allowed to participate.
4) Get noisy to different media about why.
5) When protesters assemble, loudly offer to sponsor a meet between “males and males”.
I’d wager that this ‘transgender’ swimmer has not undergone any sort of medical transformation beyond growing his hair and maybe some hormone shots if even that. The real think to do is to require that a ‘transgender’ wanting to compete as a female undergo the full transformation. My bet is that he wouldn’t do it.