According to your logic then of only the top 5% being throttled, if I'm at 2GB and am throttled and someone else is over 10GB, how would I fall into the top 5%? I just think that's incredibly unlikely. I've read up on this a lot and the most logical answer is that it is location based. I live in NJ right across the river from NYC, so I'm in a highly populated area. If I lived out in the middle of Kansas or something I probably would be OK w/ my 2GB's of usage.
It might be one of those things that depends on ARPU... if you're an otherwise very profitable customer (have unlimited texting, use next to no airtime, have a lot of crap features, etc...), then they might not want to risk losing you over a couple dollars worth of data. But if you're a customer that the company can "barely" profit on, they might actually be willing to lose you