People get to have opinions, it doesn't constitute proof that they did something, you need actual proof for that. Otherwise we'd convict people based on them having a motive alone.Alright, then let's transpose the example into exactly the same context: a criminal proceeding.
It's protected speech for a suspect to talk at length about how much of a good idea crime is. That isn't direct evidence that they committed the crime in question. And yet, look, there's a consequence: it obviously speaks to the suspect's character, and may well be brought up in court.