I think there are a few simple criteria to discriminate between legitimate opponents and others: spreading disinformation, bad faith, populism, the absence of a coherent political discourse, etc. If a government identifies illegitimate opponents based on these criteria, I’m ok with that.
So, what makes you think these accounts were legitimate political opponents?
You seem to believe that Trump saying “fake news!” is enough to consider that something is actually fake news. Anyone with a bit of critical thinking can verify this kind of affirmation and decide for themselves whether Trump is right or wrong. There’s a difference between a truth and a belief, but your argument seems to equate the two.
If a judge in Brazil says an account should be banned because it spreads disinformation, I can go and check what was posted and decide if it’s indeed disinformation. Now I might not have time to verify every affirmation like this so I tend to trust the judicial system of any country by default, unless I have reason to believe they can’t be trusted.