Customer supplied SB6121 and Static IP

Greetings,

Can someone actually explain why a static IP can't be used with a customer supplied SB6121?

There is absolutely no technical reason for this.

It should just be an issue of:

1) I assign the IP/Subnet/GW information to the router on our end directly, and it ARPs out the IP

or

2) I supply Comcast with the MAC address of the router, and it gets assigned the static IP on the lease request

So, can someone actually explain why my company can't use its own modem?

Thanks.

-Jason