Terrag

The territories are claimed by the griefer, so OP can't claim them anymore at least. In those cases someone would claim the tile adjacent to the market then erect a wall to block it, it isn't a tile owned by NQ but still prohibited by NQ.

NQ has already taken a stance on this issue, this situation is akin to when people were blocking the warp gates or building walls around districts. This is intentional griefing/considered to be pvp (inside a safe zone) because of the intent to "attack" other player's ships, NQ has made it clear that this isn't allowed.