I do not think that allowing people to sue gun companies for not having an external safety is a good way to accomplish the goal, if the goal is actual safety.

If the consumer protection bureau of a state wants to make an external safety a requirement for pistols sold in the state, I think that is a legitimate use of government authority and is used all the time with other kinds of products. Personally I think such a proposal evinces a complete lack of understanding of modern handguns and I would be opposed to it, but it is a legitimate use of government powers, and is not just a back door way to sue a disfavored company out of existence.

For this particular case I think that discussing external safeties is a distraction. In my opinion a handgun should not discharge under any circumstance where no one and nothing pulled the trigger. As a firearm owner I have that expectation of every firearm I own. I deliberately chose not to buy an Sig 320 because of the large number of reports of accidental drop related discharges; it makes me think that there might be a design defect.