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.
As non-American, the reason I think that Democrats didn’t release the list was that not only were some Democrats and their donors on it, they knew that they would be crucified by Republicans and Americans for it. The also knew that at the same time all the Republicans and their donors on the list would be let off because laws, morality, ethics are only ever to be used to oppress the poor and non-whites or to combat Democratic politicians. Do you think Trump would ever have made it to President as a Democrat? There is a reason he switched to become a Republican.