Is it customary to discuss novel idea in front of doctoral review committee?
I have been faculty in a program that did something like this. But the presentations were more open. Other doctoral students and many involved faculty. 

Ideally it shouldn't be a problem. People should be able to give candidates advice after seeing what they are working on and thinking about. 

However, if it is a problem, and you have reason to fear people will steal ideas and develop them before you can, then you are in the wrong university with the wrong faculty and I advise you to make a fast exit. It is really an unethical atmosphere if this does happen. 

Back when I was a grad student we had a small seminar with a few students and some faculty. There were only six or so of us. But we discussed things pretty openly. There was no problem and no fear that there could be a problem.