Not for nothing, but those units have long favored and issued 1911s. You probably know as well as I do that some orgs have biases toward particular platforms - sometimes for good reasons and sometimes for less defendable reasons (for example “We are SWAT/Special Operations. We are more qualified and need a different pistol to prove it.”)
I’ve not read anything about why USMS SOG switched. If you’ve got info that didn’t come from Buck at STI, then I’d be interested to see it.
I’ll be more impressed when agencies start turning in G17s for STIs.