I can see both sider actually...
Look, you surely can not blame Comcast for wanting to limit a new service to folks that already have reneged on paying for another service from the same company. If you owe me money, i may be understandably reluctant to have you take on any more debt with me.
However, the other side of this is that internet service is used for many productive things that cable t.v. is not, including access to services, including medical, and information that can include job searching sites, educational information etc.
I think that Comcast is being over-villanized over this, but perhaps taking that requirement away is not without merit.
Deeds, not words