Its a pretty good guide. And I'm sure it would benefit from any attention you give it.

I'm also partial to JWWeatherman's Yeti Cold stuff as well as Ben Westgate's Bails concepts. Neither is perfect, but they show you a different way of thinking about Bitcoin security.

I think that that tutorial is a great starting point - just needs updates and maybe some more vetting where it talks about 3rd party stuff. It's MIT-licensed so anyone can pick this up. I'd just fork the repo and start editing, talk to Mike if you feel like this is something worth your time and want to move it further. The main thing here is testing.

I can pledge you a few h/week of my time for review or 3rd party code assessment if you wanna do something like that.