and you know why trump did this? to "set the tone" for when he pardons stone

this is blatantly tied to that
It may be part of a ploy to normalize his subjective pardoning of corrupt figures, but I think he's really using this pardon as a bribe to get dirt on Obama and "corrupt Democrats."
Ask yourself why else would Trump, who has made it clear he uses his presidential powers only for his own personal gain, pardon a Democrat convicted of corruption? This is a man who leads "lock them up" chants at the mere suggestion that a Democrat did something wrong.
Its because he knows the guy is corrupted, susceptible to bribes and would happily go along with Trump's personal agendas against his former party in exchange for getting out of jail. If hed do it to the duly elected President of Ukraine, and get away with it in a formal impeachment trial, you can bet your ass hed do it to a shunned, compromised convicted felon Democrat he just released from prison. I can almost guarantee Trump made that "i need a favor though...so about Obama" call before the man had a chance to hug his own family.
This is the country we now live in under Trump, Barr, McConnell. A straight up banana republic where no information can be trusted and elections are now decided by lies, conspiracies, corruption, smears, cheating, disruption, bribes, back-door deals and money rather than the free will of an informed public electorate hat Democracy relies on. This is exactly where Trump, McConnell, Fox News and the Tea Party/MAGA Republican party wanted to reduce our political discourse to so that they can "own libs" at the expense of their own integrity.
Democrats should not reduce themselves to the behavior of Trump or Republicans but they need to wake up and fight back. Stop thinking all these formal processes that Trump, Barr and McConnell are systematically corrupting anyway or "the American people" too stupid to think critically about Trumps lies and smears are gonna protect Democracy and put a stop to this shyt.
To some extent, within the scope of truth and ethics, they gotta be willing to get in the dirt also smear and expose the ever lasting shyt out of Trump and these Republicans. They have to be willing to engineer public opinion the same way they do. At least until this shyt is over with.