I hate the way he did this....but I agree that if you have done your time and are not on probation or parole you should get all your rights back.
Though I feel the responsibility rests on the citizen to follow up with the restoration process.
I also do not assume that most convicts are democrats. Most AA ones probably are, but many white convicts are right leaning for sure.
If the governor pardoned before their time was up, your assertion doesn't apply. They would have not served their time. For political reasons, they were released early. It is strictly a political move. It should not be allowed.