If, i sustained injuries after a tough battle, the last thing I would be thinking of is having sex with Mercy, even if she is a healer. Imagine this was healing sex? The longer they have sex the better Pharah's recovery with be!
I'm also a bit of a RemiFura fan, and honestly, I used to hate this pairing because of that. But with the Touhou fandom, it's inevitable for you to love the ships you hate. Just wait for it to happen =_=