very true, but you're going to run into the sweat issue no matter how you carry it while riding. Fannypack might make it at least less likely. Also some models have a stainless steel option to protect the surface

Although I carry my cell phone in my pocket all the time without a case and it doesn't get wet with sweat unless it's a super hot and muggy day, most of the time it should be OK. Any gun you carry-on you should be in some sort of holster anyway, and that should protect it for all except the insanely hot days. Perhaps an open top neoprene pouch would work