I'll go further: it's very common for abusive people to intentionally misappropriate the vocabulary of people they abuse. This ranges from "telling me to clean up after myself is a microagression" to "we're going to name our fascist party socialist LOL."
Someone's waving their power around, plain and simple.
Perhaps, but I think sometimes we are very eager to label people as abusive or toxic as a shortcut to understanding them. So I would avoid being too casual with permanently categorizing behavior of abusers.
I have also seen mental illness lead to behaviors that one could call abusive, gaslighting, etc. The wrong kind of label doesn't get those people where they need to be.
Microaggressions are definitely a thing and one misuse of the word does not invalidate the concept. If you see a misuse of the term 'sexism' it's not okay to say "I suppose this is the natural consequence of making 'sexism' a thing." The same is true here.