I do not believe that this is a reunion of players from the same team, PCL or other for a few reasons. #1) Individuals are a range of ages #2) PCL PLayer reunions, for the most part did not start taking place until the late 1980's / early 1990's well after Bill Tozer passed away....
It could be a baseball player "Dinner", of which there were hundreds hosted over the years just in Northern California. Several cities had 'oldtimers' organizations for retired players including San Francisco, Oakland, San Jose and Stockton. Most of these organizations held monthly meetings , as far back as 1941, plus many hosted special dinners. These organizations welcomed players that were former major leaguers, Pacific Coast League, California League, as well as other minor leagues as well as those who played "semi-pro" ball. There was usually a requirement that the player was born, lived in, or played in the city that he was being recognized as an 'oldtimer'. Since Tozer played for the Seals in 1914, he could have been a member of the San Francisco Oldtimers.
Although many players ended their 'professional' careers by their late 30's, many played at the semi-professional level for many decades. One catcher that I knew played until his early 80's.
You may want to check John Ward's site on semi-pro baseball in California (
http://goodoldsandlotdays.com/). There are literally hundreds of team's listed with thousands of articles and group shots. You're unlikely to find a perfect match, but you might be able to pick out a few faces.
I do agree with your guess on the photo's age. Mid 40's-early 50's is a good start