The Current FGM Staff lists the members of the TC and says the following.
Trade Committee - If zero to one TC members are involved then trade must receive four approvals. If two TC members are involved then trade must receive three approvals.
Their are currently 7 members of the TC so a trade can get 3 Vetoes and still get four approvals and pass.
I believe that the TC might have expanded from 5 to 7 to include alternate members in the case of absence, but the rules were never changed to reflect the increase in size.
Under the "old" rules when the TC was 5, more than 1 veto effectively invalidated a trade, because it could not mathematically receive 4 votes.
I suggest we resolve this issue, because there might be some members of the league uncomfortable with a simple majority determining whether trades will be approved.