I think SF has a point in as much as gay people's interests can conflict with a religious person's interests; just as trans people's interests can conflict with female's interests.
However, he doesn't communicate that feminists concerns are not about the letters used on a birth certificate but rather the entitlements that come with it.
Despite all the posturing that 'transwomen are women', according to the Equalities Act, if they have a GRC, whilst they are 'legally women', are should benefit from the related sex based protections that come with this, they also have the protected characteristic of 'gender reassignment' afforded to them by being male. This in itself proves that they are not the same as natal women.
He also fails to point out that same sex provision affords privacy, dignity and safety. When same-sex provision becomes same-gender provision, it fails to afford the dignity and privacy that comes from women resting assured that a male-bodied person will not be able to enter the provision at any given moment. Where the rationale for the provision is based upon our sexed bodies, it is non sensical to suggest that the sexed body of a natal male is inconsequential.