this is like saying that a user doesn't actually agree to anything just because they clicked "accept" in a EULA. you're just clicking buttons in software, it doesn't obligate you to anything!!! but actually yes that is most likely fairly binding in a lot of jurisdictions.
that is, again, literally the definition of a clickwrap licensing agreement and you cannot do that in GPL software, even if it's non-monetary. Requiring the user to submit a selfie in a funny hat would not be permissible under the GPL either. You can't limit what the user does with the software and how, or else it's not GPL.
it's open and shut, clickwrap agreements completely subvert and nullifies the moral stand the FSF is trying to make. And it doesn't matter how innocuous it seems, it undermines the whole point of the exercise.
fortunately the GPL includes a "severability" clause that basically allows you to ignore this and grants you a license regardless. but it is not a good look, it is not good behavior, and if every GPL'd package started adding random clickwrap agreements with big "IM A DOODOO HEAD IF I IGNORE THIS" parameters the whole ecosystem would degrade.
Arch and others are not only allowed but actually morally and practically in the right for stripping these messages, and it doesn't reflect well on Ole at all that he then goes on and throws more tantrums because he doesn't like the consequence of the license he chose.
If he wants to go proprietary, or BSD (which requires acknowledgement!), that's fine, but he's being a child and the terms he are adding are utterly uncompliant with GPL, and it's unprofessional for FSF to even humor him on this. If there were a hundred Oles the FSF would have a real problem on its hands, it's only because he's N=1 jerk that this is remotely tolerable.
