I should spend more time here! The performance/interpretation made me laugh, which may or may not be a good thing!
Anyhow, Barenboim is one example (no doubt there are others) of a pianist who takes quite a few liberties with J.S. Certainly he throws in quite a few octaves where they absolutely were not intended! Witness his WTC interpretation, both Books 1 and 2. Yet, I confess to liking it very much (well with a few exceptions).
The problem here, I think, is not the introduction of octaves., etc., etc..., which can "work", or at least work for me, under certain circumstances. Rather, what is a little bothersome is the technique: there is "good" octave-playing and "poor" octave-playing. Just as there is playing that is "even" and "uneven"; and pedaling that is "clear and unobtrusive" and pedaling that is messy to the extent that it's hard to hear what's going on.
If you were to clean up the technique in the senses mentioned above, at the very least, then I guess I might (as a listener) be in a position to say what I think about the tempi and the octave-playing!
Music (like all art) in my view is something that from an epistemological standpoint is "in the mind" and there only. In other words, I don't subscribe to the "objectivist" thesis: inter alia that there are "right" and "wrong" interpretations. Rather, there are interpretations that are in "good" (generally accepted) taste; and there are interpretations that are in "poor" (not generally accepted) taste.
"Taste" is itself, of course, entirely subjective. But it can be measured and tested, nonetheless. More precisely, taste is "intersubjective": a perspective that is honed, developed over time, culturally relative, and subject to widely held views on what "works" and what doesn't.
Interpreters violate taste at their own peril, I suppose. But it doesn't make what they do "wrong" or even "bad" in any objective or scientific sense. That's just not what music's about for me.