Let's try to summarize what he tries to say but kinda doesn't do very well:
_Rust and OpenBSD are not a good fit._
OpenBSD keeps to certain aspects about how to do thinks which just don't work well with rust. This doesn't mean they are better or worse. They are just different.
For example outside of rustc-dev hardly anyone compiles rust them self. As such not many work on making rust compile itself on exotic systems (and yes in 2020 i386 is a exotic system, even through it was the standard in the past). I mean improving cross compilation is for now much more important (as far as I can tell).
But OpenBSD requires the ability to self compile and support hardware for a very long time so rust (for now) doesn't fit.
Another example is that many rewrites of classical small tools provide little value to anyone _if_ they are 100% compatible. As such they tend _to not be compatible_ in favor of better interfaces/output etc. (E.g. ripgrep!!)
Lastly OpenBSD is stuck in a world where thinks move very slow. But this is also why many people use it. One the other hand rust is from a world where thinks move much faster, sure with small steps and backward compatibility but a small step every 6 weeks is still a lot over a fiew years. So they just don't fit well together.
I also believe that in the future they might fit well together at some point. But not for now and probably not in the next 3 or so years.