Ofc I would let him save me first. It's what happens after being liberated that concerned me. Before calling him a slave liberator I would definitely make that backgroud check. If i was to find he once dismissed his own slaves without proper compensation based in human rights and equality, then my next moral task would be to prosecute him.
I mean, please correct my lack of american history knowledge if necessary, but the way I see it is really easy to dismiss slave labour only once you get the industrial machinery.
Butcher knife is always gonna lose to hand pistol.