EDIT 2: I wrote a blog post that makes my stance clearer. The below is kept for posterity.
It was my idea that put demanding the return of prize money on the table. (I did not directly suggest doing it, for various reasons; but I did entertain the idea.) It was also my idea to disqualify the works retroactively. To be clear, I am not an organizer of gbcompo23 or gbcompo25, nor am I involved in any of the teams, nor am I a moderator of the gbdev Discord, or anything like that. I was consulted purely on the basis of providing a personal opinion. The full conversation which led to this is available on the gbdev Discord in the #homebrew-hub channel.
I believe it is unfair to benefit - especially financially - from a community effort, then turn your back on said community. It is your right, you are correct in saying so, but it is also a bridge that you are burning and you must be aware of that. I made the suggestions mentioned above in this light, after consulting some other people to get a reality check myself.
The administrator of the website in question, Homebrew Hub, is Antonio Vivace. He also operates the gbdev Discord and organizes gbcompo. There was no solution in which taking a combative stance, even if justified by law, would lead to “major Game Boy publishers” not finding out - because these people all talk to each other, because all of these projects are highly interconnected.
The rules state, quote, “Submission will be published and kept online for free on the competition website”. You are correct that there is no specific time period listed. However, at no point was it stated to be specifically Itch, either. The website which hosts the rules is gbdev.io, not itch.io. The rules say published, but they don’t specify by who. An interpretation which sidesteps linking to authors’ Itch pages completely is, therefore, potentially just as acceptable. I don’t know - I ultimately recommended Vivace to get a real lawyer before doing anything extreme, but it would probably be much more expensive than it is worth.
It is really unfortunate that they were written so imprecisely, but I suppose the organizers felt it was unnecessary to be pedantic, given that the communities Game Boy homebrew owes its heritage to (in particular the demoscene) see this kind of redistribution of competition works as a kind of common law. I am pretty sure this will be amended for future events.
For whatever it’s worth, I recommended removing the works irrelevant to gbcompo immediately, as my problem was specifically with what I saw as a break of its social contract.
EDIT: After getting a broader sampling of feedback online, I agree that suggesting an escalation all the way up to “return our prize money” was a mistake on my behalf. Even if I pointed out that it was a nuclear option with massive asterisks and did not recommend in the end, I should have pushed back on taking it that far, as maybe some of this could have been avoided.