Not really, hence the qualifiers of potentially and necessarily and so forth. We've seen him operate astrally with no body to tether to, but not killed physically while projecting. Essentially my notion here is as long as his astral form lasts long enough to do up the Flash and a while longer, that's a win. Or possesses the Flash or etc. But it's all dependent on that and the notion of that since he's already projecting, he's already left his body, as it were.