I get everyone's problem with it. But I think it's actually one of the few things straight from Giger. I haven't the slightest idea if he would approve of the scene itself, but he always insisted that the Alien was a kind of beautiful thing, so the creation of the first of its kind (at least to David), is that its a beautiful thing not unlike what HR Giger thought of his initial creation and his work on Alien 3.
It's a stretch but I think it's a reference to Giger's belief that the beast was, in its own way, beautiful. And almost sort of a posthumous tribute to him.