I used to think he sided with the libs because of his adopted kids but they’re adults now so what gives?
I don't know, but some possibities:
Is there a citizenship issue? If the adoption was irregular, this could come up, and I would not put it beyond the RATs to accept Obozo on the most flimsy lies, but try to blackmail Roberts on the issue.
The kids are still only young adults. If kids the same age are shot holding up a store they immediately become "child victims of gun violence". He does not want his own children to become child victims of political violence.
The kids are probably in college now. Lots of potential stigma.
It would be embarrassing for Roberts to have something illegal from his past come up...