I'll put this up front, just to make it clear: I'm not going to sit here and say that advertiser's should hold any power over what we say or how we say it. In general, modern advertising is a cesspool of shit.

With that said, advertiser's have one main goal, to reach their target audience, and endear them to your product so they go out and buy it. If you're advertising on a platform like YouTube, there's going to be a nontrivial amount of pretty much every demographic, which is uncomfortable with such difficult topics or the words associated to them.

So I don't think it's surprising that they wouldn't want to advertise to their demo along side content that would upset or otherwise make their demo uncomfortable.

Building on this point, advertiser's are just reacting to a very real issue that some have with some words and terms. They might be upset or triggered or otherwise made uncomfortable/unhappy by hearing some things being said; I think it's respectful to those who would be triggered by other terms for "unalive"