There has always been players who intentionally lag blocks entrances in towers. This mostly happens in mod tower.
As you can see in the picture above there is this guy with the smiley head who frequently
lag blocks (or however he does it ) the entrance to the flag room in mod tower. I assume his accounts gets banned for it however, this doesn't stop him from doing it over and over again on alt accounts. I'm sure some of the GP team became familiar with this guy. Today morning there was no admin online so we had to wait around 20 minutes not be able to access mod till AJ came online.
Therefore this is what I suggest to be implemented to stop these type of players who intentionally blocks the flag room entrance while they're un-hittable wither it's caused by lag or hack. Players who don't move inside the towers for several seconds should get a warning similar to the warning you get when you're inside a house. However, if the player don't respond to the warning he should get warped to the spawn room. (this shouldn't happen if the player is afk inside the spawn room) This would be a good fix if they block the entrances using lag. If not, I don't really know what to suggest to stop them from doing it.