Iac, so what? In the Gemara there are machlokot between Amoraim over what their rebbe said – and both even swear to it. I even heard of a modern case where they argued as soon as they left the rav’s home. Of course, it could also be that you heard wrong. So far as I know there is absolutely no makor for saying that they are safek chametz. What Rav Belsky might have said, which I did hear, that the minhag was adopted because of a marit ayin – kitniyot are used to make bread (corn bread in particular was very widespread) and people would think that it was regular bread.
Ubi, here in Israel there is a hashgacha that specifies that it is kitniyot. I heard that with the growth of the Orthodox Sephardi community in the US the OU also has such a hashgacha now.