Using a maintained and up-to-date browser is a reasonable requirement for an IT department (should be for anyone really). Would you suggest they should be allowing IE6 just because a user might prefer it?
Of course Google is going to suggest using Chrome, if they detect that the browser might be out of date.
Is the implication that Firefox is not maintained or?
The issue presented doesn’t seem to be “an up to date browser check” it seems to be a “is it latest chrome” check, which is a very different thing.
Strawman argument. Firefox is maintained and up to date browser.
Why did you even compare it to IE6, out of the curiosity?
If that's a the goal, then IT department should start by blocking user ability to install Firefox or other unapproved software not by blocking access to google workspace. Blocking access to google workspace using Firefox doesn't prevent using it for everything else. It's not like the google services are going to exploit a vulnerability in Firefox, everything else might.