Good work. Looks fairly conclusive, and I would tend to agree with your conclusion, but I'm curious if there were other days the teams crossed paths, the playing in the game part isn't relevant, it's all about being in camp (which doesn't necessarily mean being printed on the roster or playing in the game).
With no disrespect meant towards the daughter of Mr. Morton, her opinion on the happenings years before her birth are not something I put much weight on.
When asked about wearing different numbers during his career, Stan Musial himself had no memory of ever wearing anything other than #6, yet there is documented evidence of him wearing #19.
https://thecardinalnation.com/now-ba...tanley-musial/
Unrelated to your quest, I just realized that Guy and Stan both played their ML debut games on Sept 17, which is kind of weird, but not completely since I would guess that a large percentage of debut games happen in September.
Also, did you know that Guy Morton's father Guy Sr. played 11 years for the Indians?
Last in the dumb trivia department : your Guy Morton, also know as "Moose", was according to his Retrosheet stats 1/2 an inch shorter than I am, while being 5 pounds heavier. I have NEVER been referred to as "Moose" so if I want to be, I guess I need to gain those extra pounds.