That may explain WHY he said it; but the statement IS true: MORMONism is a cult.
(You don't have to be a genius to figger THAT out!!
So?
Like I've been saying, we were not hiring Romney for the job of spiritual leader. By voting for or against him, you are expressing judgement on whether you think he would be a better candidate than Obama, for the particular and specific job of President, which entails (1) working to preserve the constitutional freedoms of US citizens, (2) not messing up the economy, and (3) keeping the US safe from foreign attack.
I've hired a number of people over the years. My hiring decision is based on whether I think they can do the job. Their religious beliefs are generally irrelevant unless a case can be made that the religious belief would interfere with their doing a good job in the slot that I'm evaluating them for.
For example, I would pick a Buddhist or Hindu who was diligent in getting the job done, over a Christian who could not get along with others or who spent his time berating others about religion.