Can't you play with historic decks in the normal queues all the time? It is shit and they need to change it, but what he's saying is factually incorrect as far as I know.
I also think Pioneer should be a long term goal for Arena and was never going to be realistically obtainable in the short to medium term, and already starting with the "arena needs pioneer" videos just comes across as whiny from content creators who have to put a video out every week. Dropping that many sets responsibly would take a couple of years in itself.
It should absolutely have a roadmap though, and WotC really need to better integrate the side team responsible for the Arena client into the teams responsible for MTG the game. At the moment Arena is missing clear leadership, extremely reactionary and feels outsourced at best.
Yeah, he should have been more clear in his video. What he is talking about is Historic events, those will be held once a month.
In the meantime, you can play best of one Historic matches, but the games offers no incentives to do so, it doesn't even count to your daily rewards, and there are few people playing, so you can get paired with the same opponent several times in a row.
And everyone that I saw speaking on the topic, including the professor, is not demanding Pioneer immediatly on Arena, they know that it will cost a lot of time and resources to program all these old sets into Arena, but they should at least commit to it, even if it takes several years, and in the meantime, support Historic, with best of three queues, ranked and events, things that MTGO is already doing with Pioneer.
And speaking of MTGO, when it first lauched, it didn't have all the sets. They added them in bit by bit, took some time but eventually they did it.
So I think it's not unreasonable for them to do the same for Pioneer.