It’s scaled depending on where he is when you damage him. They said a long time ago the base XP award for killing a guys isn’t very much at all, he has to be near the objective for it to be worthwhile. It’s supposed to help vs spawncamping because you won’t get much XP for that.*
Back in the early days of ETQW on the old forum site I did a series of posts titled “XP awards which reward positive behaviour” where I suggested just such a mechanic; areas built into the mega texture where bonuses for things like kills and revives are multiplied. This was to replace the “defend the objective” mission (where every defender got XP no matter what they were doing) and the one that never worked for the attackers to support the guy doing the objective.
I remember one very good comment at the time against the idea was that people would then wait until the enemy was almost on the objective before killing them, therebye actually making it’s defense less likley. I still like the idea though, I think most people will kill you as soon as they get the opportunity regardless and it probably will tend to push people towards the objective more.
*re spawncamping, to me it’s a valid tactic: you are interdicting the enemies re-inforcements so they aren’t available at the objective. It does suck though when a team gets stuck in their spawn to the point where they can’t get out, so I know how it can become really frustrating and I think it’s valid to try and keep that from happening. It’s one of those slippery slope kind of things.