Can you at least be happy?

Bear's therapies are going well. Up to three in home appointments a week. This past week has been filled with some significant gains. I try to tell the parents and I get a shrug. They say he isn't old enough to be evaluated and that he is just slow at developing. I understand developing at a different rate. But there are some HUGE red flags. I want them to share in my joy about their son but I don't see it happening.