回复：请问各位兄台, 他这样写究竟是什么意思

I think you may be a bit oversensitive. Americans say "
stuff" all the time.

In your email, you said that you wanted to talk to him when you hand in the stuff and I guess he didn't expect to have a talk. His email probably just indicated that he would be there to listen to you but he may have nothing much to say.