If the cats were just back from being "fixed", they might have been upset with his wife. If he was getting the idea "KILL" from cats he was spraying with drunken spittle without giving them treats or catnip, it wasn't his wife the cats wanted dead.

The only good part is that he missed his wife, and he wasn't still on the road that drunk.

He probably thought when the cats growled they were agreeing with him instead of just warning him to shut up so they could go back to sleep.