Could try to prehook AddPromptToIncomingQueue and cancel the call when the interact type is INTERACT_TYPE_TRAVEL_TO_LEADER:
Lua Code:
ZO_PreHook(PLAYER_TO_PLAYER, "AddPromptToIncomingQueue", function(self, interactType)
if interactType == INTERACT_TYPE_TRAVEL_TO_LEADER then
return true
end
end)