Basically, if you've done something wrong, but can drum up enough support for the winning political candidate, you get a chance to cut a deal and wipe the slate clean.
To those that say he's rehabilitated etc, I'm sure there were other worthy prisoners too, but why does this particular guy happen to get the pardon on day one?!
Same with the pardoned capitol rioters.
It just feels like a very slippery downwards slope, where political back scratching trumps everything else.