Popa:
I can’t claim to speak for Modern Orthodox people, but leshitascha that R’ Aharon Lichtenstein “is definitely Modern Orthodox”
( http://www.theyeshivaworld.com/coffeeroom/topic/thoughts-on-the-yeshiva-gush#post-337966) I can tell you that he did differentiate between halachic and non-halachic questions:
http://www.theyeshivaworld.com/coffeeroom/topic/daas-torah-2/page/5#post-525980
But I think there might be a more fundamental dispute, and that is what I mentioned earlier about using the pasuk of v’asisa as the source to follow a rav in actual halacha. Someone might say that that would be directly against the pasuk. The pasuk is saying that there is a Sanhedrin which everyone is bound by, in order to prevent everyone from having their own Torah. So it might be construed as somewhat ironic to use that as the source that everyone should have their own Torah (i.e. follow a specific rav).