If someone makes unethical moves (like taking peoples twitter handles or boosting alt-right memes), it makes sense to assume that unethical behavior is more likely in the future. The reason people get angry with you is that you don't maintain the same "reputation score" in your head within the brackets they find acceptable. That is, I allow for variation in perception to some degree, but if at a certain point someone says something really admiring of someone who's proven to be wholly untrustworthy or destructive over and over again, as a matter of public record, I start to judge that person as unreliable and lacking in judgement. This often comes out as anger, I think because it's a simple way to use our social emotional brain to "keep score".
(This is particularly applicable for individuals and individual actions; it's more difficult to apply this rule for groups. For example, do you have great faith in "academia"? This may or may not be acceptable to me, depending on your definition and your knowledge.)
Your simplistic view of wanting to have a villian to hate who is always wrong and bad in everything they do is a very childish perspective, one that is sadly all too common online these days.