Since old-Ansom would have considered new-Ansom an abomination, I wonder if Charlie assumed that Jillian would dust new-Ansom out of loyalty to the values of old-Ansom. Charlie hasn't had the same face-to-face contact with decrypted units that the units on the scene have had, so he may not realize how vividly alive they are.
2. Convince Jillian to turn back! It's not clear that Jillian would go back and deal with Wanda even if Ansom were dead... although it does seem marginally more likely that she would go back for better or ill. He may be thinking that Jillian could be bribed to head back into the fray if Ansom were removed from the picture... or would do it for Jetstone's sake.
Maybe he thought that Sammy would appear to be croaking rather than capturing Ansom on his own initiative, and that Jillian would be more favorably inclined toward Jetstone if Haggar were the ones who croaked Ansom.