Maybe we should look at your question from the opposite side. What is the validity of assumed spirituality in absence of consensual reality? In many respects, deep spirituality is integrally linked to the depth of reality of one's life (my opinion at least).
I think that's a very fair question and one that fits with my own sense of spirituality. Despite being rather devoutly anti-organized religion, I've come to love Jinja Shinto (as I loosely understand it). Largely becaus of its emphasis on the natural world; on understanding the world around and within us through observation and intuition.
The tough thing for me in conversations about spirituality is that it seems like anything goes...in other words, it regularly doesn't seem to seek consensus from the physical reality we seem to live in...per my perception of it, at any rate. I'm an agnostic precisely because I seek that agreement from my 5 (or 6?) senses.
I don't think others have to do this...and more to the point I don't think it's possible to judge others' perceptions in this regard. Nao Deguchi sounds like a lot of people I've seen on the streets of Seattle and Everett, never mind the even more interesting world the internet gives us access to. And yet, here's a person who sparked a tremendous spiritual influence on a relatively large number of people. I think a lot of people would write her off as a kook and yet because she lived in the untouchable past, she's given more authority. I apply this example to the Abrahamic religions as well. Prophets tend to be...well..."interesting," to say the least, but because I think of spirituality as the relationship between individuals and the "meta," I cannot judge them very far. Where I start to judge is where it impacts others; where it seeks to interject between the relationship of other's private relationships with that "meta." Even in that case though, I feel I have to respect the fact that people are autonomous individuals who will do what they want anyway. All I can do where I think I see a problem is offer the most reasonable or otherwise virtuous observations I can muster. I used to talk to some very frightening groups of people (Joy of Satan, anyone?) trying to critically evaluate and demonstrate holes in their attempted logic, but it rarely worked. That it didn't seem to work only made me try harder and I think if anything I only served to further entrench them in their views. I think it was the perceived oppositional nature of my language. This is an extreme example, but I think the principle holds true in more benign cases too.
That all said, despite my strong affinity for scientific methods, I'm very proud of my Celtic and Native American heritage and often look to their surviving concepts for an understanding of the Universe. It's just another lense I use for trying to make sense of something vastly too...er...vast, for me to comprehend. Mythology and the like doesn't have to be correct in order to serve a valid purpose. If someone wants to literally believe a Crow swallowed the sun I don't think it's necessarily invalid even though I think that's impossible in the conventional sense.
...A bit of a ramble, sorry, but I hope that answers your question.