Personally I think you are confusing your own opinion for everyone else's. It would be a divisive appointment but the fanbase is not universally against it. He had decent support as an option on here in the poll. And I know other blues who while not enamoured with the prospect of him are not ardently against the idea. Those people get drowned out by the keyboard warriors. If we're winning then most people will support him, look at Moyes at WH. They will be quick to turn back against him but for now, a pretty much universally disliked appointment is popular and supported
Most people have awareness the options atm are not great.
If he'd started here, left for Liverpool acrimoniously, then tried to come back, it'd be different - 100% would be against him, a la Nick Barmby.
There's no doubt there will be a massive pushback to Benitez from the fans, no denying it, and he'd be pressured out if results are terrible within six months.
But if results are good, the idea that fans would boo him and be holding protests is laughable.