Should I be offended?

My mother sent me this joke:

Some cannibals get a job in a big corporation on the condition that they don't eat any of the other staff. Things go very well until their boss calls them into his office one day and gives them some bad news--a janitor is missing in mysterious circumstances and the cannibals are under suspicion.

The cannibals get together after work. Their leader says, "Which of you idiots had the janitor?" One of the cannibals raises his hand.

"You idiot! For weeks we've been feasting on team leaders, project managers and human resources staff, then you go and eat someone they'll actually miss!"