While V24 is the heavies life for the most part, if you TK so often that you've been kicked, then let me assure you-its not the odd random potato who walked in front of you-its YOU SPECIFICALLY shooting at that single dude swarmed by 3 friendly melees, because you just can NOT let go that 20 exp or you thinking you're a tactical, walking thorough the doors instead of taking longer approach that would give you high ground and better overview with no one around to stand in front of you.
It needs a review fullstop or to be purged completely. The amount of people I have seen abusing it recently is nuts. A guild doesn't like a non guild person? Kick. someone gets into an argument with someone? Kick. You get TK'd for standing next to a tank when it explodes? Kick. I even got a vote to be kicked the other day as soon as the fucking game started for some trollish reason. The feature was designed to deter trolls, instead it gives them the biggest fucking trolling weapon I have ever seen implemented in a game. Seriously have no idea what they were thinking putting such a lazy, thoughtless system into the game.
Have you tried letting your team know you were setting up to cover the stairs with a Plasma Cannon? Something short and simple in chat like "Got PC, covering stairs, keep clear" works for getting the point across to otherwise unaware teammates.
You know where your team's melee guys are going to run yet continue to fire there. Coordinate with your team if you want open fire lanes.
5 users outside a capping point all about to storm in. No time to warn. You have a shot charging ready to take them all out. At the last second you see a Leeroy Jenkins wannabee running towards the door. What do you do?
As death Guard i take the shot, as ultramarine i will try to kill a bird...or move my aim to get my team mate on the AOE border. But mostly i stop shooting PC as soon as my team advance, change my position and reattack on a new vector. Or i switch class... So many things to do...
In that case? Fire. But you've described a last second in the moment of a single shot kind of situation instead of one with/without established firing lanes. The OP was talking about firing down the stairs on the fortress map and killing his team's melee guys often enough to get kicked over it. That's a clear lack of communication.
Done a few TKs using the PC, though never got kicked because of it. Seriously, blaming the team mates getting shot is like a driver blaming a pedestrian for getting run over. If you are pulling the trigger, you are the one responsible for who gets hit. If you get kicked, it's your fault.