Camping is bannable, but first you need video evidence, not screenshots since you can't judge the time elapsed in screenshots. However, in order for someone to be banned for camping, they need to make the match last forever and impossible to win. However, if you are able to get to this player, it won't be camping since you have the ability to make the match end. Bannable camping would be things like making an Obsidian room of 30 layers surrounded by lava and water.
So it is a bannable offense, but the player needs to make it impossible for someone to win in order for it to be considered a bannable offense. You also need to record the camper and give him warnings, in case you ever find a player that is making the game impossible to win.
If you have more questions, feel free to private message me about it.
~Locked