The Commando character was the prototype for Michael's game. A long while back, before (or after?) E3 2001, fuzzy ED screens were leaked out on the 'net featuring a person with desert fatigues and a rounded kevlar U.S.-style helmet, arguably the Desert Storm trooper. Denis Dyack did mention many changes were made to ED's storyline, and was eventually re-written so that the vast majority of the playable characters would be "regular people," chosen to be heroes. That helps explain why Pious Augustus seems to be the only hardened warrior/killer among the playable cast, and thus doesn't lose sanity at all, probably due to his battlefield experience.
What's left of the commando himself is the corpse Michael encounters at the beginning of his chapter. Looking at the commando's uniform and weapon loadout, he may have been U.S. Army Special Forces.
Also, in one of the old Silicon Knight/ED wallpapers, there's a husky bald man in the dark background depicted (use a photo editor to lighten the picture) who obviously did not make the final cut.