It definitely is.
Also, I think you get the mech armor if you defeat one of the enemies on B1 or the final area and then use your splash attack to revive it. The mech shouldn't disappear once you "kill" it and the mouth thingy shouldn't be there once you've done so.
The mech also has a few special properties. If you use the masturbate command while in it, it can refill your Splash meter (and maybe health, but I always use the infinite health trick) at any time and it'll also heal the mech at the same time. Also, any time one of the girls is inside it, she won't follow along automatically and stay in that spot wherever you leave her. Getting out of the mech is as simple as pushing the button which usually undresses her.