I have some knowledge of this person and the situation.
Curtiss trained with Hove Women's RFC from 2012-22. Hove Men's RFC have three men's teams, and a Vets team. The Sea Serpents (a specific LGBT team) also train at Hove Rec where Hove RFC are based.
Curtiss has plenty of playing options with other biological men. The only option closed to him now is playing with Hove Women's II. This team has a lot of experienced players, but is also the funnel from the U18's team, so has a lot of players aged around 18/19 every year. The majority of these players are fit and athletic and about half the mass of Curtiss.
Changing facilities at Hove RFC are limited, and many women chose not to use the facilities. However, Curtiss is a heterosexual male, who has implied in his blog that it would not be safe for trans women to use male facilities, so we can guess that he would choose to go in with the women rather than men.
His desire to be part of Hove Women's II is just about validation and gratification. Nothing else.
It is great to see the Crowdfunder being subverted. Bring on the challenge!