I am not offended. I find special underwear for religious purposes to be amusing.
A clerical 'dog collar' identifies the priest, and serves a function within the social group, but underwear is not visible,and can have an effect only on the wearer.
In the 'toon, that is not an accurate depiction of Mormon garments. It lacks holes in the required places. I also imagine that Romney has knees that are less knobby, since most men's knees are less knobby than those of the 'toon Romney.
I would have no problem in voting for a Mormon, even if he wore undies from Victoria's Secret. I don't much care for Republicans though. I don't expect Romney to get the nomination, though I might be wrong. He LOOKS more presidential that any of the others. McCain looks too old, Giulani lacks hair, and Paul is too short. Between Huckabee and Romney it is a close call, but Romney is taller and has a much better profile.