As long as copyright exists, we need copyleft licenses to ensure that covered software can't be copyrighted.
That is to say, being against copyright doesn't mean you want to allow others to abuse it against you.
That is to say, being against copyright doesn't mean you want to allow others to abuse it against you.
The only way people can "abuse copyright against you" is if someone claims you violated their copyright, and invokes a DMCA takedown request, or sues you. You using the GPL will not protect you from this in any situation I can imagine. In fact, what Drew is doing here (claiming violation of copyright) is literally the only way to abuse copyright.
But, even in that case, you have lost nothing. Other people doing anything with the code you released, including making restrictively licensed derivative works, does not harm you, cost you anything, or deprive you of anything you already had.
Not believing the (or an) idea of copyright is one form of being "against" "copyright". One can oppose copyright law while still desiring a form of social enforcement for copyright-law-like ideas. Just as there are many forms of emotional abuse that are not illegal or could not be enforced if made illegal, and just as there is such thing as "abusing one's trust", there are forms of copying behavior that deserve the label of "abuse" regardless of whether the law gives a label.