I have never seen the sense in a fundamentalist approach to aikido. A fundamentalist approach looks at O Sensei's teachings and tries to figure out what they were and go from there. If the evidence of your very senses contradicts what you think O Sensei's teachings are telling you, then you have to ignore the evidence of your senses and cleave to a "truth" that you don't experience.
I think your point of view lacks nuance. You don't have to choose between following O-Sensei 100% uncritically (fundamentalism) on the one hand, or ignoring him completely on the other. Any teacher, living or dead, will take you places you couldn't have got to on your own; that's why they're teachers. If the evidence of your senses contradicts their teachings, it could be that they're wrong or misguided. It could be that your senses need honing. It could be that you're misinterpreting what your senses are trying to tell you. It could be that the teacher is pointing to areas of experience you have no clue even exist.
In my experience, if a teacher is worth learning from, most of the time when they tell you something that makes no sense, it's the last of the above possibilities that's operational. So though O-Sensei's spirituality was pretty much opaque, I find value in continuing to struggle with it.