It wasn’t about video length, it was about the Twitter leadership at that time being categorically incapable of monetizing any of their products.
Combine that with the orders-of-magnitude higher cost of running Vine compared to the bird, and it was always either going to be sold off or shut down.
It’s easy to forget that this was back in the time when these companies thought they were changing the planet for the better and drinking their own Kool aid by the gallon.
His actual goal is in the final sentence of the article and has nothing to do with moral intent.