Lots of companies run $1 transfer promotions every now and then, or cheaper in the case of at least one large company I can think of, running promotions isn't that unusual. Free, less so, sure, but taking out their issues, if indeed there are any, on customers isn't going to help anyone here.
The whole 'email' thing coming from Network Solutions really seems to have little basis, because it wasn't personalized or described as such. It seems like more of a way for them to avoid acountability.
Emails are forwarded, codes are shared. That's standard. People share with colleagues, wives, friends, whoever. Companies usually want promotions to be shared. Also standard.
The code was unrestricted, unlimited. Nothing said otherwise. Company reps also stated this.
Not that I am suggesting that helps any of us affected, it doesn't.
Personally, if Network Solutions are okay, I will be happy to use them in future. I imagine others also would, if they are better than their past reputation. The whole locking people's accounts thing whenever is unacceptable and the Auth Code stuff doesn't sound good, but if they do offer major discounts for renewals, like someone suggested, I would certainly consider staying, and/or using them as a registrar in future. It's not much, but better than a load of angry customers, issues, complaints to ICANN, business bureaus and wherever. So, hopefully they will behave reasonably. Remains to be seen.