Yesh it is and because they have no life and like trolling on team mates lolz.

Because they're DOUBLE AGENTS o.0

same reason why trolls use escort, they keep an eye on who is about to call in air support like a Pavelow or overwatch and use it before they can. That or the Strafe Run but most trolls i run into aren't talented enough to pull that off or they're smart enough to realize that the escort lasts longer