I enjoyed the video and agreed with most everything you said. I do think watching the video if we are truly picking a winner between the a1 or Z9 the a1 actually won. If discussing a system then it becomes very personal for what your needs are which Steve mentions. Keeping that in mind it appears to me the reason the Z9 was picked was more about the system i.e. lenses more than the body itself.
I have no doubt the Nikon eco system offers a lot of options. If I had the opportunity to replace my 600 with one with a good built in TC I would in a heartbeat. I think for the vast majority of those who shoot wildlife they won't spend the money on a 600F4 and if they do many will look to the used market which doesn't exist with the new Nikon 600 with TC. The vast majority are 200-600 buyers which for now Nikon doesn't have. At the end of the day unless you are willing to spend big money on the primes or the 800PF I think the case could be made that Sony actually has the most diverse system currently. They also have more than one body that is capable of producing outstanding results for wildlife shooters, there is a used market allowing more people to have gear they desire/need at a more affordable price. The a1 came out of the box with more capabilities than the Z9, yes the Z9 with updates has caught up but considering the a1 is over 2 years old that speaks to the system, its abilities and the future is bright.
It is pretty impossible to pick a bad system to invest in or update. Canon, Nikon, Olympus, Sony and Fuji all have a system that can capture images that the DSLR would be more challenged to reliably capture.
It is all subjective as to what one values the most. I welcome the comparisons and I think it helps many who are on the fence or starting from scratch. Not many people (myself included) have both systems with that much time behind the camera to even begin offering an honest comparison.
For me the customization of buttons, speed of switching from one shooting mode to another and having the ability for 30FPS in RAW when wanted is a very compelling feature set I am not willing to give up.
It is a wonderful time to be a photographer and investing in new gear!