Dear Anonymous,
I don’t know if Rav Moshe did or didn’t. I’ve asked Rabbanim who should know and did not get a clear answer. He writes in one teshuva that we can assume a Coservative Rabbi is passul leydus even if he is known to be observant. This doesn’t mean that the Rabbi is automatically to equated with his Flock. By the way, I am not assuming that Rav Moshe agreed with those that held Conservative Pulpits.