My shadow is kinetic and level 47. Do you play on The Bastion? I'd be careful about paranoia.
It's an unfair tactic and should be fixed (like jumping over the gap in VS, which was fixed), but they are just using what's available to them. Exploits are more serious than that, like planting from inside the wall or abusing the old Voidstar ramp. Where something is clearly going wrong. Placing an AoE doesn't qualify on that level.
Edit: Nice try editing out your accusation.
I checked the logs and it wasn't you, but yes i do play on the bastion - which is where that video was taken from.
It is something that's available to them, but calling it "unfair" isn't being honest about the ramifications of the tactic. It's exploiting the terrain by placing an AOE above players, from a position is totally safe from any attacks, while preventing the attacking team from moving forward for an indefinite amount of time.
Only one class can do this effectively (and you'd need 2-3 of them to keep all 3 from getting capped). Every other class will either have resource maintaining issues for their ground-targeted AoE's or cooldown timer issues.
Also, there is a way to counter this, though it's technically an exploit of its own and requires that you'd be a certain class and/or spec, so I'm not going to explain it.
I play a sorc and can tell you with certainty that i could prevent any team from progressing beyond those walls in a voidstar match just by using force-lightning ontop of that wall from the safe side. All it would take is someone healing me while i consume to replenish the cost of force-storm for 5-min straight. That's not "unfair" - it's unstoppable.