I love him. I consider Kirk to be the ultimate chad and a lot of it comes from Shatner just being Shatner. I think he's putting it on a bit and leaning into being his "difficult" self a bit in the video but I'm pretty sure he sustains himself with his ego at this point anyway so it is what it is.
And yeah, sure he's had work but no amount of work keeps you that sharp at 90. Man is a living legend.