It does not provide any additional value, since that can be faked as easily as the screenshot. Any validation requires something from Twitter end-point, that they check and verify publicly that it actually existed at that time… but that does not work since we are going against removals made by Twitter in the first hand.
Thats a lot of effort going into something that 99% of the people couldn't care less.
Exactly, so using a screenshot is in fact a good solution
Apart from the inefficiency and inaccessibility.
It'd be pretty easy to automatically implement in their publishing system, I think.