/logout should be disabled in survival (via dimensions) to prevent exploits such as:
Godmode due to tshock disabling guest users and restoring hp (or risk updating tshock)
Npc item duplication, as items placed in an npc inventory as guest will be restored when the player logs in once more
Disabled users cannot move so logging out can keep players at the location of their death upon respawning
Placing/using banned items (that are not projectile or tile banned) is possible right after logging in (clears the disabling buffs immediately, so the item use animation can continue)
/logout should be disabled in survival (via dimensions) to prevent exploits such as: