There's no real way for liberal actors in our political system to talk about political violence in a way that makes any sense, since they're all theoretically targets. So they have to say bad. Impeachment (and a confirmation of it) is the only legal process intended to serve as an alternative to assassination, but it failed with regards to Trump and this time he's just a candidate.

Using violence to stop someone is also a slippery slope because objectively Biden is responsible for far more human life years being lost than Trump though, no matter how one slices the data. That's the difference between being a middling businessman mostly licensing their name and being president 4 years versus a 50 year career politician who championed all of the US' worst moves both at home and abroad.