What you're effectively saying is that Vettel got lucky with the onboard camera angles, and kept his mouth shut after the race, so he should be allowed to get away with no further punishment because it can't be factually proved it was an intentional collision.

Looking at everything in context, it's painfully clear that the move was intentional. No way do I buy a 4-time world champion conveniently losing control of his car in the middle of an angry outburst. His ignorance of the incident after the race only cements that he knows he did wrong, and if he doesn't acknowledge it he thinks he's safe.

Instead of trying to find any way of shutting the book because he's already had one form of punishment, let's actually look at what happened, and make sure it doesn't happen again. We have a driver that last season had verbal outbursts in a fit of rage, and then pulled a dangerous defence that he spent most of a season up to that point saying should be outlawed. Fast forward a few months later and he's deliberately driving into someone that's annoyed him under safety car conditions. What's the next level of escalation? Full on ram at race speeds? Vettel needs penalising heavily to discourage not only himself, but others. Shifting the argument to anything other than this is trying to let Vettel off with what is widely deemed as too lenient a punishment, regardless of how you try to justify it.