This thread is neither capable of distracting me from noticing nearby people with guns, nor capable of alerting nearby people with guns to my presence, so I find your premise to be flawed.
It's not. It's the engineer nearby who's just been alerted to your presence, and knows exactly which direction you're going to be looking.
Who's already dead, 'cause the first thing I do when I see a spitty is look for the poor idiot that's almost certain to be babysitting it.....
And you somehow have seen him, before he sees you, despite him presumably being ready for you, or at least alerted to your presence, while you're having to deal with fire from the Spitfire turret the whole time you fight him?
Not unless you've already walked over his mine at the door. It's all a game of preparation against enemies versus preparation against enemies.