All,
I think there's big confusion here between what's called in the industry "Settlement Free Peering" and "paid transit services."
Comcast offers "Ethernet Dedicated Internet" service in my area (Washington, DC). They offer: Static IPs, DHCP and a BGP session. In this service, Comcast will not allow the user to BGP to a third party with the intention to use Comcast for carrying the 3rd party's traffic. This is simply called "paid transit service". When we refer to getting a BGP session with another AS for AMPRNet, look for "BGP transit service" plans.
Peering would be considered traffic between Comcast and another large ISP (i.e. the peering agreement would be relevant if e.g. USCD - AS7377, wanted to peer with Comcast). That's called [settlement free] peering (in a Tier 1 ISP's terminiolgy).
About the product: https://business.comcast.com/enterprise/products-services/data-networking/et...
For a list of cities with the product: https://business.comcast.com/enterprise/products-services/data-networking/me...
73,
- Lynwood KB3VWG