CAn't see this doing too well in court.
Just had a quick look at the Comcast Residential Agreement (Link)
Section 6.b.1. says that Comcast can send code updates to your router at any time they like; that these updates can change, add, or remove features; and that these updates can be used to provide features not just to the customer (i.e. you), but also others. It also explicitly mentions this WiFi hotspot function when explaining this.
I am going to guess that this agreement will be the defence's 'Exhibit A'.