I am not sure anyone can assist. I have never heard of a Congressional waiver for AFOQT. I am going to assume that you ask them to step in and force HQ AFROTCs decision to be overridden by your MoC.
I have heard of cadets/officers to request what is called Exception To Policy (ETP), but it is rare to get an ETP, especially as a cedet. The reason why is many fold.
1. MoCS don't like to get involved unless there is some true reason/proof to get involved.
~ They know that this decision did not come down to disenroll you from an O5 at your unit, but it went up the chain to HQ AFROTC,
2. The MoC will be shown that you did fail it twice. 4 points or 1 point, the pool of AFROTC cadets passing still is more than enough for ADAF manpower needs come 2017
~ What will be your defense of why they should give you a third shot? If the MoC said yes, they will get involved, how will you convince them that you will pass it this time. Not only pass it, but be a superstar?
Failing it twice means two different pools were stronger than you. Many cadets do not take the AFOQT more than once, thus they could see it as two year groups that you competed against during this exam.
I am sorry if this seems harsh. I get you are trying every path, and you should. I am just saying if you go down this path of ETP, what is your defense of why the MoC should do it, since right now all you are is a cadet, that is not even a POC yet. I can see if this was something to request if you were a POC about to commission in a few weeks with an insanely high cgpa from MIT going as a Missileer, but right now they don't even have a guarantee you will graduate from SFT and become a PoC.
Go for it because you can't live with a What if, but when you do just be prepared to defend your position of why when they have enough commissioning via AFROTC and OCS to fight with HQ to overturn their decision.