Again, Delta Force isn't the name of the unit nor do members of it even use that name informally. Furthermore, it appears that the crux of the complaint deals with a logo that absolutely has no relation to the unit itself or the name Delta Force.
And if I'm not mistaken, context also plays a role in things like trademark disputes. The fact that we're dealing specifically with videogames here and not two vastly different things I think is going to be of some assistance to them.