He set out to improve things, which is a good goal. Improving means criticizing the status quo at some level. In case of academia, with tenured people lingering there for life, status quo is probably the result of their work (for better or for worse). Wanting to "improve" that was probably perceived as an insult something like "what you did before sucks, I'll make it better". Unless he was dealing with unusually rational colleagues, that stuff is never forgotten and surfaces at voting times.

But also playing devil's advocate here. It could also be that this is a "well the grapes are too sour anyway" type story. That is, maybe his research wasn't seen as very good, innovative or interesting to deserve a tenure. Maybe he knew it too so set out to instead focus on teaching and other aspects. I've seen people do that. Can't code so they become really strong proponents of documenting everything, or they look for other busy work to justify their salary. That is not necessarily all bad or wrong, but it is interesting to consider here. We haven't really heard from other side so to speak.