Can people look to the OP for how "religious experience" is defined? The topic is not if theism is true or whether experience is "valid".
Thinking the moon is a god isn't an experience...
The link cited in the Op actually does present us with that option.
Did Moses think God was manifest in the burning bush? Yes.
And it clearly met the criteria of numinous awe.
When I have migraine auras, there are blind spots in my field of vision that are eventually swallowed up by fiery sparkling lights, a real showy storm. One might even call such an experience "numinous." I don't think the old Moses and I are related but certainly I'm not the only person in history to experience migraine auras, there was even a recent thread about same discussed here.
All translation and mistranslation issues aside, even if we were reading an accurate reconstruction of the original author's intent, it doesn't mean Moses witnessed a burning bush. Seriously, it's dopey, and I could think of far more convincing experiences to play on old Moses.
I realize that migraine auras don't sound as fantastic and wooish as a fiery bush but in terms of natural explanations it makes sense. I think the verse even says the bush was on fire but untouched, which means it really wasn't on fire. Could easily explain those "pillars of fire" too.