You've referenced "TiVo update" in the subject of your post, but posted in the TV360 section.
This provides a query that's also part of the answer. TiVo-firmware is licenced in by VM, whereas the Horizon-firmware that drives TV360 is in-house to VM's parent company, Liberty Global.
VM want to migrate TiVo users onto TV360, and thus anyone who wants their TiVo/V6 updated, will be recommended accordingly. I'd go further than nodrogd's point that you're "unlikely" to get anywhere, and suggest you simply won't.
Regardless of functional differences between the two, VM regard streaming & "online-first" as the future, and thus TiVo as legacy.