We had this same thing happen on our server before (Im CPT Franklin from the 506th PIR) we consider it an exploit on our server to completley box in the camp, or to use repair trucks to box in the depo. YES, the walls can be destroyed and are a great asset to assist in defence, we do not frown on using them to construct defences around those areas. however if you use them to completley enclose an area, we will kick you from the server as a warning, and if you do it again, you will be banned. In the spirit of fair gameplay, you should leave at least 1 opening to enter and exit from, at that point it would only create a chokepoint and an obstacle to breech which is fine by me.
using the walls to directly box in and kill players or destroy vehicles i consider cheating. both, boxing in camps/depots and players/vehicles i view as a tactic created by those who suck too hard to be able to directly engage and destroy thier enemy. In addition to their overall lack of skill, they typically continue to play with complete disregard for what the team is doing and do not help acomplish the goal of thier commander. i say this because i have seen this tactic used a few times, by players that were nowhere near the area the rest of thier team was operating in. These types of players i will personally ban for the hopes that they go buy BF2 and can play a game that suits thier nub style.