Absolutely it's on you. If you gave £2000 to a smackhead then complain he spent it terribly yes, it is on you for not doing even the bare minimum of due diligence. If I decide to buy a construction company in which i know nothing about and constantly override decisions made by people who know what to do in the construction industry, yes, it's on me.
Have them take some responsibility ffs. They are the reason we are in this predicament. They are making an appointment they know is going to be MASSIVELY divisive and for what? What reason can they POSSIBLY have here? Theres NOTHING about Benitez that even whispers "yeah, he'll do good here". He's a manager who is massively past it, plays hugely negative football, falls out with owners and is an odious tit.