I'd disagree here. Being as it's Virgin Media who update the V6 software, it would be down to them to add an Amazon Video app to it. This would of course be dependent on them getting an agreement with Amazon to do so, so you're possibly half right.
Virgin however do play their cards close to their chest, so I wouldn't expect any information about an addition to the TiVo firmware until they were ready to publish it.
Of course this doesn't stop them from passing the suggestion up the chain.
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.