I understand the whole "rules are rules" argument, however I'd be cautious when dealing with the investigators and consult an attorney before signing anything. If AA involves their legal department, you should too.

At the end of the day, if this was your only offense, AA would be foolish to penalize you, if you fly as much as you say, over it. Do you fly on paid premium cabin fares?

And, at the end of the day, they do make the rules, but there's no reason their T&C can't be challenged.

So, while I agree you shouldn't lie to or avoid the investigators, throwing yourself at their mercy and being thankful for any penalty the impose short of revoking all your miles is equally foolish. They stand to lose a lot as well if you choose not to continue your relationship with them. In fact, since you don't really use the miles, they stand to lose a lot more than you. YMMV.