I'm really not sure why people think there would be any significant PR problems if they were seen to be condoning porn. Sure, there might be a handful of people yelling "think of the children", but cracking down on porn would piss off far more customers than allowing it, especially with current tensions over fair use.
Besides, every single game/movie/show/etc that has achieved even a basic level of success has plenty of porn based around it already, yet I don't remember a single instance of this really being a PR problem. Creators get criticized for having sexual content in their work, and people who create porn get criticized for sexualizing certain characters, but I don't think I've ever seen the creators of a work get criticized for not aggressively abusing copyright law to crush porn they themselves never created. I'm sure there's probably some lunatics out there who would do so, but I'm not seeing any evidence of this being a large enough trend that we can assume this to be happening here.
Probably the closest thing I can think is with MLP and Zootopia. Although there might have been some people urging the respective companies to crack down on porn, the criticism was aimed at those creating the porn, and that was really only due to these works being clearly aimed at children. Overwatch may not be adult only, but it's not really aimed at children either.