This seems vindictive.
That said, being escorted out by guards is a GOOD thing. It covers your butt if something goes wrong shortly after you leave. People do some stupid petty $hit when they get let go, justified or not. SOP is to lock out your computer account BEFORE you are notified (Nothing on that computer or network belongs to you so you have no right to it anyway) and have guards escort you around as you take personal items, clean your desk/area, etc..
It's better than putting your faith in the good will of someone who is no longer obligated to listen to you, and is probably in a bad emotional state. If even 1 in 100k people did something crazy, how many computer network crashes or even burnt down office buildings would there be?