Romney’s politics are irrelevant for this post, as the same hypothetical would apply if Harry Reid were running for President.
How does an LDS President attend a Temple session? Can enough LDS secret service personnel be found to accompany him through a session? Does the Temple have a strict no-gun policy? Would he just not attend for 4 years? Would the DC Temple become a security concern, or a potential terrorist target. Would it be swept for bugs? Would Temple Recommends be heavily scrutinized to prevent someone from faking their way in to get at the President?
Has Romney or anyone else asked these questions?