I don't care whether it's validating or not.
Nobody should care whether it's validating or not.
I don't think strip searches are generally validating, regardless of anybody's gender identity.
Other things which are not supposed to be validating: using the toilet, seeking refuge from domestic violence, going to the gym and using communal showers.
Female prisoners are searched by female prison officers because they are the same sex, not because they share the same identity. If trans women were actually being treated the same as female prisoners, they would be searched by male prison officers because they are the same sex, and their identity isn't relevant here. Insisting on being searched by someone of the opposite sex is being treated differently to women. It isn't being treated the same.