This is just tit-for-tat clickbait. The researcher’s wording was a bit unclear for sure, but far from incorrect.
If it just found existing solutions then they obviously weren't "previously unsolved" so the tweet is wrong.
He clearly misunderstood the situation and jumped to the conclusion that GPT-5 had actually solved the problems because that's what he wanted to believe.
That said, the misunderstanding is understandable because the tweet he was responding to said they had been listed as "open", but solving unsolved erdos problems by itself would be such a big deal that he probably should have double checked it.
Note that “solved” does not equal “found”