When did I say I am asking for dedicated circuit?
I actually granted that congestion could and would happen. I pointed out what happens if someone decides to saturate the line... would last only few hours each month before quota being hit.
What you are granting Comcast doesn't make sense technically, financially, legally or ethically. Don't open my packets other than headers for destination. Don't look inside the data of my packets. Don't offer intermediate certificates posing as proxy for end site. All those things are fine within a corporation's privately owned network. Comcast is similar to post office, they are not allowed to see inside my mail to see if it goes to bank or to insurance company, just the address on the envelope can be used. It is none of Comcast's business whom I talk to and what I talk about and how much I talk. As long as I am under quota and under bandwidth limit, they must carry the traffic.
In the catastrophic event they can stop traffic to certain IP address segments to keep voice lines and emergency sites accessible. They can work that out with regulators like for 911 service. But they can't use that as a way to extract payments from content providers. Complete stopping is preferred over degraded service. Comcast would have to come up with justification why they stopped the traffic, degraded is just a play to get ransom payment.