He pretty much accuses him of skimming without using the words. He did mean it as an insult to put Moe on the defensive and take control of the conversation to tell him he was going to be out of the casino business one way or the other.

Whoever said it was Moe, not Michael who first brought up the issue of skimming is on to something.

.....It was his way of pissing off Moe without directly accusing him of skimming. It was Michael's way of getting Moe to bring up the skimming himself. ....