@djjd62,
He didn't get fired for making jokes, he got fired for costing the company customers when his sole job was to try to gain customers.
If he did it just by poorly doing a duck voice they'd be right to fire him too, and you'd be wrong for saying he got fired for making a duck voice. No, he gets fired for bad job performance.
He makes jokes all the time and didn't get fired, so they clearly have no problem with jokes, and even offensive ones (he has no other brand of humor really), they have a problem with him loosing them clients when he's been hired to gain them and why shouldn't they?