Just give customers what they're paying for
For the most part, every customer of an ISP should receive the same service, meaning whatever service level they're paying for. As long as there's no congestion, no one's packets should be inspected or filtered in any way for the sake of "network management". Where the customer's traffic is going and where it's coming from off-network to the ISP is none of the ISP's business--the customer is the one paying for access.
Now, when the network does become congested, as it most certainly will for a huge operation such as Comcast, then some management becomes necessary, but not the kind that's been implemented by Comcast. Customers who pay more for higher speeds (aka more bandwidth) deserve a higher priority; customers who pay less deserve a lower priority. Customers who use more (and huge) amounts of bandwidth should receive lower priority; customers who use less bandwidth should receive higher priority. Balancing these priorities is true network management--something Comcast is unfamiliar with. In all cases, every customer's traffic should be respected as a matter of simple privacy (not that there truly is such a thing) and honest business practices (all customers deserve to get what they pay for without any bias on the ISP's part relative to any application or protocol that is inherently legal, as BitTorrent is).
If an ISP is going to sell a product, then it needs to supply that product... to EVERYONE who pays for their services. Comcast's recent behavior with respect to network management constitutes nothing more nor less than breach of contract. Killing someone's connection through forging packets is not network management. It's denial of service. It's fraud.