Well, there was authentic influence from Ravi Shankar et al, and yes religious/spiritual fascination for many in the culture during the whole decade of the 'sixties in the US. Miles did use sitar and tabla in 1969 and I think it was more for texture and to bring in "hip" instrumentation or introduce novel sounds.
I was all in on Miles' "New Directions in Music" when "In Concert" was released and jumped right onto that and followed everything Miles released after that. For me MIles' music has always seemed a world of its own. Even as far back as the Prestige days there was something fundamentally unique about much of Miles' work. A good thing.