What is wrong with just following standard VFR’s?
Staying clear of the clouds is easy.
This is an example of clueless idiots in charge. There is always some risk to everything. The only way to eliminate all risk is to kill yourself.
Because when it concerns volcanic ash...VFR rules don't work. You aren't just trying to stay out of the "cloud" and you can be VFR for days and still have enough ash in the air to stall your engines (if you are a jet).
Ash builds up over time on the engine...so even if you can't see it...its slowly building up in your engine...and grinding the little pieces down.
There is also the little problem of abrasiveness. Even if there is just a little bit of it in the air...it's abrasive. When it hits the cockpit window, it scours it (almost looks like a frosted up window). Then the pilot can't see whether its VFR or IFR. You want to fly with a blind pilot...go ahead...
And doing that is, well...risky! You could end up dead!