Turn off guild invite was a change done in cata but it's a simple change, nobody is going to make an uproar about being able to turn on or off guild's spam inviting them.
Many leveling guilds will simply invite you on the principle of you not having a guild. Some players want to play in peace without an invite every 5 minutes. Neither player is in the wrong, but (in my opinion) Warmane's in the wrong for not allowing the player himself to have incoming guild invites ignored just like you can ignore trades.
This is a simple change but should be implemented.