He was not doing what he was paid to do if he was presenting himself as a woman. It was deception. Clearly the marine would not have participated if he knew the prostitute was a man. That should be considered sexual assault. It was not consensual. The marine did not consent to having sex with a man or even a transgender nutcase. He was tricked into it.
You can attempt to rationalize this any way you choose.
The marine set this in motion by consenting to pay the hooker for some kind of sexual experience. What kind of experience, we just don’t know.
You don’t have license to kill people, not even tranny hookers, for fooling your sorry ass.