Well, I think you’ve misunderstood the whole thing, and referring to Mattex doesn’t make your case any better:
"I'm not interested in an artificial concept, I'm only interested in the Reality of the whole situation."
Mattex is spot on, at the right place and time. You are not.
What is "real"? The art or the artist? If the art is perceptual, that does not change the rules or our science and the way we practice it, only the way we understand and approach it. Possibly with a little more respect for the artist and the art.
The way it all makes sense to me, time and space are continuum and the present time and space are all that we exist in. The past is only history, the future, only possibility. Present is what we are stuck with. Lucky us!
"All the world's a stage, and we are merely actors." Shakespeare, I think.