Mercury has it’s own set of problems on top of being antimicrobial. Along those same lines, I suspect we’ll rue the day that salt became “bad.” It’s an excellent preservative, and like most preservatives, it’s antimicrobial. Losing the salt in canned goods is going to make an outbreak of something nasty and food-borne more likely, imho.
The retort cooking specifications for canned foods are well established. I am not concerned about some "super-bug" in canned goods. The added salt concentration in canned foods is for flavor enhancement, not preservation. Salt preservation in foods works best in conjunction with dehydration - think of fermented sausages, country ham, sauerkraut.