Rubbish. Think about when you go somewhere totally new and out of your comfort zone- it would help if you had your partner or a familiar friend there with you wouldn't it? Of course it does- it gives you some security while you suss out this new place and how things work. So I absolutely think you staying for a while will help your son to orientate.

That said, I know what the director is getting at as some parents linger in a way that makes their anxiety obvious and that doesn't help the child feel secure. If you can stay and show your son that you are comfortable in that environment, then start by leaving him for short periods as Kazbah suggested I think it would really help.