For me, baiting would be staying in spawn while pointing your gun at an enemy, or jumping around in a conspicuous and provocative fashion in plain view of an enemy in an attempt to get them to shoot you. Similar situations with vehicles could include sitting in a helicopter or revving a jet on a runway for prolonged periods of time when an enemy is known to be watching for you to leave spawn, or aiming at them with a vehicle. Basically it's any action that stops short of a hostile act ( shooting, leaving uncap, deploying equipment like MAVs, UCAVs, mortars, etc ) but which is likely to elicit a reaction by an enemy player.
To put it in a different perspective, baiting could effectively be considered a form of griefing for your own team. The person baiting the enemy player(s) is not actively attempting to play the game. They are instead wasting both their own time as well as that of their team in an attempt to cause an enemy to break a rule. Their act of baiting is potentially depriving their team of a resource they could be using to win : specifically the slot in the server the baiter is occupying.
It's also just kind of douchey. You're acting in bad faith to try to get a person to break the rules when they might not otherwise have done so.
The real problem is people are too report happy. Every single instance of being shot in uncap does not need to be reported. Sometimes people make mistakes. It should only be reported when it becomes a persistent problem with a player, especially if they have been warned against it in game. For example, just the other night I was shot by someone while he was running through the uncap on Locker when his team did not have all of the flags. I could have reported him if I wanted to but I didn't because it was just a one-time thing and he apologized for it.
I know a lot of you guys want some kind of black and white rule book but I don't think you're going to get it. Some situations are too complicated to give a hard and fast definition for everything.