At least in Maine where I am, TWC does allow you to bring your own modem as long as it's DOCSIS 3 compliant and there's lots of those from motorola, netgear and others. You're not stuck with the Ubee.
You are ignoring the "BUSINESS CLASS" part of the equation. TWC-BC provides the modem for you; you have little (arris) or no (ubee) access to it.
