fly, That's just being on a farm/ranch and being prepared for rattlers or aggressive/rabid wildlife. For what ever reason he became (in your view) "not a gun guy", that doesn't mean he suddenly turned into an anti-gunner. It just means his needs changed.
My grandfather was an avid hunter growing up, mainly because if he didn't hunt, meat on the table was scarce. He was the oldest of 4 boys and great-grandpa was off in the Army (WW1). Squirrels, rabbits, possums, coons, deer,... if it moved and he could see it, supper it became.
Then came the Depression and WW2. Only this time it was for his own wife and kid.
After WW2 and the end of rationing, he seldom hunted because he no longer needed to. He had become successful enough to be raising his own beef, pork and mutton and was running a meat locker plant. He once said that he had killed and cleaned enough animals, he didn't need to go hunting. He still had a shotgun and a couple of rifles for varmints. Unlike some of his brothers and cousins, he never developed a "need" to have the latest new gun.
I'd bet "something happened" that contributed heavily in his decision to not have guns around.