I can't give you sound bites that will make this all instantly clear, but be assured that:
Billy is perhaps the single most unfairly maligned individual in all of American history, 130ish years of propoganda notwithstanding.
People who say "harrumph" to a pardon are simply ignorant of the facts. If you look at the truth, the whole truth, and nothing but the truth, the Kid deserves a pardon. I would much, much rather have to explain why Billy got a pardon than why he didn't.
I don't care a whit about the politics surrounding of all this. Gov. Richardson is doing the right thing. He's being a statesman, not a politician.
BTW: There was never a "wanted" poster issued for the Kid. The one you show is bogus, as are all the others.