It's bad for OpenAI to go after a blank website, which could develop into anything, not necessarily related to their GPT product. Other than that, this is exactly how trademarks are supposed to work. OP should just calmly tell OpenAI that they are not infricting on the trademark, because it's not in the same business domain.
I get that people have a negative attitude towards the company because the "open" in its name basically turned out to be massive bait. But this is business as usual and trademarks exist for good reasons.
The problem is precisely the spamming of takedown requests without doing any due dilligence that the target actually does infringe at at all, essentially offloading your enforcement costs to random individuals. IMO reapeated offenses of this kind of behavior should result in complete loss of the trademark.
I get that people have a negative attitude towards the company because the "open" in its name basically turned out to be massive bait. But this is business as usual and trademarks exist for good reasons.