It's a response to a bit of a loaded statement. What does the parent poster even mean that a descriptive term isn't 'true'?

That the behaviour it describes doesn't exist? That would be a truly remarkable claim.

That the term is inapplicable to that behaviour? On what grounds? Is there a term they'd prefer we use?

That the behaviour exists, but we shouldn't slap a label on it? That's almost certainly personal opinion, which is not very interesting.

If the OP would have instead said that particular claims about toxic masculinity are false, that would be an entirely different conversation. But that's not what they did.