Marketers have nightmares of news stories that read "brand X ran ads against hate speech and anti-vaxxers," so they'll avoid keywords where there's even the slightest chance of a PR disaster.
Question. Has this actually ever happened? I would figure even the dumbest brick of a human being would recognise the difference between randomly run advertisement and the content it was just played on. What they fear would be akin to something unexpevted and questionable happening on live TV and someone going "AHA! There was just a Coca Cola add before this, they MUST be OK with what just happened. Time for a boycott!". I do not have to tell you how absolutely ridiculous this idea is.