And this is a passed down requirement, coming from the major advertisers. Google is simply enacting their will to never advertise on anything remotely related to a laundry list of taboos. I have a vague memory of something about this being in ToS (which I read ages ago, before joining the company) and I think we got smarter about this (preventing display on particular content; think like demonetising particular videos on YT).

Source: I work in Google. Not in Ads, but this topic has been discussed in TGIF at some point.