Agree. Broadly speaking, if someone is accused of a moral crime about which you have no privileged information, publicly hypothesizing about how they might be innocent is tantamount to a defence.
It's a limit on free speech. And in private circles, it could be debated responsibly. But when stated publicly, the argument's components of character defense and appeal to rationality are confusingly (possibly inextricably) balanced, which should be obvious ex ante.