I still don't understand if the problem getting it updates is with Tivo or Amazon. Seems like they are blaming eachother from what I have seen.
Obviously Amazon would have to develop the app but TiVo has to give them access to the SDK (and probably work closely while development takes place). It also requires a licensing deal between TiVo and Amazon before Amazon will even start work on the app. So both sides have their part in this. I don't think it is about blame but about neither side putting forth much effort to get it done.
TiVo has a unique deal with Amazon. They are the only platform that actually offers downloads which are compatible with TiVos all the way back to the S2 units. If they offer a Prime compatible streaming app I wonder if they'll continue to offer the ability to download?
Developer for VideoReDo