First off the posting is incorrect, Comcast's first throttling trigger is tripped when a particular node has reached more than 80% of downstream and 70 of upstream capacity. The second trigger relates to the particular usage. Put in this context, it has less to do with comcast throttling their individuals and more to do with their outdated network. Given the proposed system it appears that comcast has found a reasonable solution to their bandwidth issues, but only because they are viewing bandwidth as a limited resource. The fact is that the bandwidth's can be greatly increased, but at great cost to comcast itself. In the end the real problem is that comcast is allowed to hook an average of 275 modems to one downstream port and an average of 100 modems to one upstream port. All of this is because cable itself is a dying medium and comcast has yet to utilize true fiberoptic networks.
Finally as a note to modem hackers everywhere.. you can't get throttled if your modem doesn't change its bootfile when they tell it too :P