Why shouldnt you be hit with the mid attack after that? If youre in stun and you think a high attack is coming, then you should only be able to high counter to get out of the situation.
The problem with the low hold is that it is too strong, it gets you out of the high attack, it gets you out of a low attack (you hold it), and it gets you out of high throws. Suddenly, the attacker, who just did the right thing by hitting you and stunning you, has his options reduced to low throwing or doing a mid, you realize how strong the low hold is?
Add to that, that if you low holded in the first few frames after you were stunned, you recover fast enough to hold the following attack, like im not saying you get stunned, hold low vs a high, and then recover to block mid. The problem with the actual build is you get stunned, you hold inmediatly after the stun hits, and you recover to hold the inmediate next attack. Say you get stunned and the next attack is a mid.. right now, if you hold on the first few frames after getting stunned you will be able to block that mid.
That is where i see the problem