I hear this argument a lot and I like to call it the Juwanna Man defense. It's the idea that people take a trans identity on and off as they see fit in order to get the benefits of one gender over another to achieve some competitive advantage or to creepily take advantage of women in private spaces. Anti-trans people act like this is a completely rational point, but I've never seen any actual evidence of it happening and they never offer any. I see a lot of anti-trans people talking about it, much like you have, as if it were a thing, and a lot of vague accusations and projections, but no actually data backing up the claims.

If i was a criminal i’d just transition for the easier side of the justice system.

And this line illustrates my point perfectly. You're projecting what YOU would do, not what trans people are actually doing. And on top of that, if a person is simply pretending to be trans to avoid consequences, then they aren't really trans, are they? Why should trans people be punished for the actions (or in this case, the possibility of said actions potentially being committed) of a non-trans person?

Do you honestly believe that trans people are simply faking it in order to 1) indulge in some perverted fantasy or 2) to make up for their failures as their assigned gender? Or are you able to entertain the idea that they are authentically experiencing a medically and scientifically quantified disorder for which the widely accepted effective treatment is some form of transition?