Don't forget Elmer was a ".44 guy" which is why he didn't push for a .45 Magnum.
Actually, his first experiments in hotrodding a big bore cartridge was the .45 Long Colt, but unfortunately he made the mistake of attempting to load a .45 Long Colt cartridge with a .45-70 bullet, and the combination of that plus the thin cylinder walls of the Colt Single Action Army he used in his testing resulted in a catastrophic failure, so he gave up on the .45LC in favor of the .44 Special, since the SAAs in .44 Special had thicker cylinder walls.
Many argue that if Keith had only been wiser and hadn't attempted to load a .45-70 bullet (which has a diameter of .458 as opposed to the .452-454 diameter bullet of a .45LC) then such a catastrophic failure wouldn't have occurred and Keith may have very well gone onto make a ".45 Magnum" but that's besides the point.
Keith was actually a bigger fan of .45LC than he was of .44 Special, but switched due to the aforementioned event.
In hind sight, things turned out for the best regardless, as Keith was satisfied with .44 Magnum, and the ".45 Magnum" as it were came into being regardless in the form of the .454 Casull and later the .460 S&W Magnum.
You are right on and so much of grandpas life was about living off the land and hunting for dinner. If you are afraid of a little recoil you should not be hunting and anyone that wounds an animal should take more time with the shot or use a bigger load. It really pissed him off when animals were left to die and suffer because someon was afraid of a little recoil. I was about 7 when he gave me a 10 guage to shoot with and it was too much for me so he gave me .22 Marlin semi out rifle for hunting ground squirrles in North Powder in Oregon each year to help the famrers. I was born legally blind and that pissed him off, so he said get the kid a bigger scope. Elmer and Bill Jordan would teach me to point shoot and didn't care about my lack of eyesight. Then a long lecture about taking my time. Squeeze the trigger and breathe in and out then wait and squeeze the trigger and shoo that damn magpie.I honestly doubt it.
Seriously, for all the reputation he has for wanting to push the envelope when it came to hotter loads, by all accounts Elmer Keith seemed satisfied with the .44 Magnum and never said anything to suggest that he desired something hotter.
If anything, I think that he would be more likely to question the practicality of the .500 S&W Magnum, seeing as he seemed adamant that the .44 Magnum was already plenty strong enough to take any game in North America.
Keep in mind, Keith's desire for more powerful handgun cartridges came from the fact that he was a hunter and was dissatisfied with the power of the comparatively weak .38 Special and .45 Long Colt loads of the time.
Contrary to popular belief, Keith didn't create .357 Magnum nor .44 Magnum out of lust for a hard-kicking cartridge, but out of a legitimate need/purpose. Yes, he enjoyed recreational shooting and was enthusiastic about powerful handgun cartridges, but he wasn't the masochistic recoil maniac who intentionally loaded cartridge past the margin of safety just for kicks and giggles that some seem to think he was.