Trump is probably on the list, so he has to protect that. The Democrats had it during their entire presidency; even if they didn’t want turmoil during their time in office, they could have released it after their presidential defeat and before Trump took office.
But still then, how would all this evidence even look like? Some piece of papers and flight logs? Even if they released all the real evidence I suspect it won’t hold up against all the people on the list discrediting it.