It seems that he was referring to the people already released with that statement, and not necessarily the murderers. Not that that makes the situation much better.
Yeah, his statement is still asinine for at least two reasons:
1) People that were already released are banned from holding certain licenses, voting, owning guns, etc for a reason. If someone commits a crime of confidence they're not supposed to be able to get a securities license and commit another confidence crime.
2) A pardon does not discriminate. In other words, pardons are unconditional. If you pardon a attorney so that he can hunt the same condition (being able to own guns and hunt) applies to all people pardoned, even those such as the murderers. Barbour cannot say "I pardon you so you can hunt and you so you can get a license, etc"; it's a blanket power that expunges everything for everyone.