However, they spell out other disqualifiers besides just a brace. The direct quotes in Post 86 clearly spell out other factors, aside from a brace.
I'm reading that a bit differently than you are. What I'm getting from it is that the "other factors" are used to determine if the brace is intended to be used from the shoulder, and then not a brace, but a stock.
I'm getting that from this,
..provided that other factors, as listed in the rule, indicate that the
weapon is designed, made, and intended to be fired from the shoulder. These other
factors are:...
and then they list those other factors as (i-vi)
As I read it, those other factors are not disqualifiers in any way, in and of themselves, they are the factors the ATF will use along with the presence of the brace to determine if the brace is a stock.
Now, IF it is determined the weapon sent in for review has a stock, and not a brace, then what? That's not stated specifically, and we are now just speculating and what they might do under other circumstances could (probably should) be different during the amnesty period.
Keep the brace and send the pistol back? If that option is offered, OK, BUT, ONLY if you give them permission to do so. Otherwise they're stealing your property. You might WANT the entire thing returned so you can register it as and SBR during the grace period. And, I don't think its reasonable to expect the ATF to keep and track your removed brace in case you do want to register it as an SBR.
I CAN see them returning the entire thing, "Stock attached" with the legal warning that if they don't see it registered or proof the brace has been removed by the end of amnesty period, charges will be filed. After all, they do know exactly where to find you...
Braces are not high dollar items compared to the cost of the gun or the cost of NFA compliance, and probably most people who do send in guns for evaluation when told they are NFA items will approve the ATF removing the offending component (the brace) and send them their pistol back....if the ATF offers that option, probably most will do it, but they shouldn't just remove the brace on their own, until after the amnesty period expires, when the rules will change a bit.