If you wouldn't force a prostitute to provide her service without pay, why would you force anyone else?
The prostitute isn't watching something burn up in flames.
There is no reason to force anything here and the bad defintely outweigths the good in this case.
-> this argument is invalid.
Your points boils down to this: "People will help me, or I will make them help me."
If you don't see the problem with this, see
here.