I think you meant to say that it was NOT political. I think Biden's pardon of Hunter was wrong, but not because it was a political move. I don't believe politics was at the center of that decision. I think the decision to spare his son the hardships of a conviction. While as a parent that's very understandable, by using his unique pardon power he engaged in a form of corruption. Though it would have been hard for him to see Hunter take the consequences for the crime committed the pardon was not justified either by the interests of justice or out principles of justice.
Trump's pardons of all the January 6 participants was definitely political. And you're right that the Biden pardon of his son gave him some cover to do it. But I grew up with the principle that just because someone else commits a wrongful act that doesn't make it right for another person to do the same thing. Trump should not have pardoned those convicted of violent crime. It was morally wrong and sends a signal that he's willing to tolerate violence if the violence is done by his supporters. That's a dangerous path as undermines support for the justice system.