The reason you are being tormented by this particular person, is probably because
1) He/She's a better dueler.
2) Your team's got no Base D
As far as my team goes, we got Base D to handle LO/Ninjas. The Base D never leaves the base, and his/hers highest priority is to clear the base of such enemy filth. If the Base D player is not able to finish off the camper(s), in decent time, the LO, or as you call, campers are going to stack at the base, and start to overwhelm you.
As Carnage defined, campers are simply, players hiding close to your base, and shooting at your team-mates randomly, with no regard to enemy/friendly flag. They do not time distraction, they do not E-grab, they do not return flags. All they do is duel and die. It's actually a loss of a player to the enemy team, if the player exhibits such behavior.
On the other hand, LO-Ninjas also duel. They specifically pick targets, especially HoF and LD, drain them of their health, so they may not have enough health to chase Cappers. They time their distraction, so the Capper may steal and escape without much notice and damage from the enemy defense. This also helps because, by hurting the enemy LD, they have a lesser tendency to catch up with the Capper, or survive after reaching the Capper's base, let alone retrieve. During stand-offs, their role changes to Ninja, for they will hide and regenerate their health, and try and get the HoF and Base D to critical, when they are supposed to receive the flag from their Capper, making it easier for the LO to kill and return the friendly flag. They are also responsible for E-grabbing, at the right time, as they need to confirm, if any of their friendly Cappers are about to steal the enemy flag or not. Otherwise, it would be Llama-grabbing.
Compare the above two paragraphs, and you'll actually know, that LOs and Campers are a lot different. The contribution a Camper makes to his/her team is insignificant, compared to that of an LO.
All you need to do, is to stop and spectate him/her. If he/she's doing atleast half of what I mentioned, an LO would do, and still gets the attention of your team, it's definitely the incompetence of your team, and he/she's a decent LO.
Also, it isn't really that surprising, to hear that it's happening in the Asian servers. So far, rarely have I seen any players who actually stay back, at the enemy base, and help the HoF clear it. Few players have any game awareness, and fewer, flag awareness. Nearly 70% of the Asian community knows bare to nothing, about the different positions a player can take up, and how effective they can be. If you really want to overcome the Light Offense and/or Campers, brief your team about the positions they can take up, and how they can help. Whatever you do, make it count.
Maxter.