It would get out though. There'd be a lot of hoops that PornHub would have to go through to make a wholly owned subsidiary they could use to spin-up a YouTube/Vimeo like platform on and it not come back to pornhub in the PR/advert sense.
Although we all know a few people here and there who don't know YouTube is owned by Google, the majority of people do understand the YouTube + Google/Alphabet relationship.