I think it was acceptable for what it was. Walker wanted to try MMA. He trained hard (apparently), and fought a guy at (apparently) the same skill level as him. He donated his purse to charity, which I also think adds credibility to the fight.
Maybe they should have marketed it more as a charity thing, but that would have taken away some of Walker's credibility I think he deserved. I don't think Walker will have more than 1 or 2 more fights (if he even fights again), so waiting till he got better wasn't an option.
I think the question is: did Walker, a famous athlete who is donating his purse to charity, deserve to fight on an MMA card? I think yes.