while you are not wearing any of this tabards, than your must gain reputation with Aliance Vanguard/Horde Expedition. But this will need clarification from retail, what reputation are you gaining, because aliance vanguard/horde expedition factions standings are cumulated from the four subfactions, divided by 2, so, if you have two of this subfactions on exalted, you have exalted aliance vanguard/horde expedition. So it needs clarification, if you really (without tabard) gain reputation with aliance vanguard/horde expedition (then it must break rule about adding and dividing subfactions reputations), or if you gain reputation with one of the subfactions (and to main faction as well) - this will not break the rule. If the second option is correct, then we must also investigate, how to choose subfacion, to which the reputation will be added and if two subfactions are on exalted, we should stop adding the reputation