*Actually paying for sex in certain circumstances is still an offence. The fact that no one bothers to prosecute or the punishment is just a fine does not make it any less so.
Street soliciting is an offence.
Having sex with an exploited prostitute, even if you didn't know about it, is an offence.
Just like someone using pot for recreational occasional use wouldn't actually end up on trial or in jail*
Under all circumstances buying pot is illegal.
The same is not true of prostitution.
I believe the above horrible and indefensible, but it is true.
While it is true I don't think it is right to stop disabled men (because it is, of course, men) doing something legal no matter how horribly immoral it is.