Replacing fuel cut-off valve with non-a/c part???

If you don't want to follow the rules.... fine..... stick to
homebuilts. If you buy a certificated aircraft, you know from the
git-go that there is a specific set of rules you must, by law, follow.

I think that's a very reasonable position from someone who:
Never exceeds the speed limit for any reason
Always comes to a full stop at every stop sign (no rolling stops, ever)
Never parks in a no-parking zone, even for a minute
Never crosses against the light
Never cheats on his taxes
And in fact never breaks any government regulations, ever, for any
reason.

Otherwise it's total hypocrisy.

"in fact it's the number one thing that brings down homebuilts in
the Phase I period"
And that doesn't suggest something to you?!?!

It suggests that the system is indeed critical. AFAIK none of those
accidents are fuel valve failure. Just because a system is critical
does not mean every component is critical.

Michael