Will request their IT Department to consider accepting/ testing end users who use Linux and or Firefox. Got to be an rational reason why this organization have ended up with this decision/ limitations.
Edit 1: Done :)
My theory to why they don't allow firefox or linux is that due to the freedom of both of them. This makes it so you can stop the website from knowing that you are not focused on the tab/window, and you can stop the website from locking fullscreen.