Meh, I'm not going to tone police the employee. It wasn't some meek "excuse me", he pretty much barged up to the counter like there was no one else there. I think she pretty much had to make it crystal clear upfront that he was going to have to wait. If you're going to (attempt to) rudely interrupt someone else's transaction, I don't think it's on everyone else to treat you with kid gloves. I also think that if such rudeness (of the "can't wait my turn" type) wasn't tolerated or accommodated so much, there might be less of it.