This is expected evidence. Cryobiologists opposed to the practice have consistently labeled cryonics as flawed on grounds of dealing with frozen bodies, not due to cryoprotectant toxicity.

And what do they think of cryoprotectant toxicity? And cryoprotectant diffusion? And ischemia?

(e.g. PZ Myers conflating E-VT with K-VT)

I don't think he did. I think he claimed that you need kinetic vitrification in order to preserve the relevant structure.

Therefore the question of whether someone in such a jurisdiction is guilty by legal standards should rest on whether the patient can be proven dead beyond a reasonable shadow of a doubt. I think this can easily be established for a straight-frozen person (due to severe structural damage to the cells), but not for a vitrified person.

I'm no lawyer, but I'm pretty sure that any court would consider a vitrified body dead beyond reasonable doubt unless you provided some good evidence that it isn't. They aren't going to buy a "You can't prove it's dead".

You are free to support suicide / assisted dying, but this is a very different matter.

Ah, sure, cryopreserved people are not dead, and vitrifying yourself while still alive is not suicide. And Heaven's Gate people didn't kill themselves, they boarded the alien spaceship following comet Hale-Bopp.

You are entitled to believe whatever you like, but as long as you don't provide good evidence that there is a non-negligible chance that the human popsicles are going to be resurrected, sane people will keep considering them dead.