I think Moses was alive here.
Exodus 33:11
11. And the LORD spake utno Moses face to face, as a man speaketh to his friend. And he turned again into the camp: but his servant Joshua, the son of Nun, departed not out of the tabernacle.
Now, lets talk about rejecting the teachings of the Prophet. If what he says as been recieved this by revelation or by communication from God, then I think his word is binding. If, however, he is teaching what he has learned, but has not been revealed, then that is his opinion, and it is up to the member to accept or disagree. It would be like your preacher saying something on the pulpit. Do you have to accept it as revelation? We do believe in modern revelation, but the Prophet is also capably of teaching by his own understanding as well.