@limab
Pure oxygen at that depth is deadly, any diver can tell you that.
I was still in HS when I read Cyborg, etc. I didn't know that, but I'm not a diver. I swam and snorkeled but never dove, because I lived/worked in aviation all my life. I was aware of the nitrogen/bends issues from reading, but not that. During initial flt training at Mother P, NAMI warned us about diving v flying. Didn't mean we couldn't, but we would be grounded for awhile. Not good when trying to earn your wings. Or by later CO's or bosses.
Caidin was a noted pilot from late or just post WWII era, I believe military trained. Rated up to multi-engine. Known to have flown B-17's. Owned and restored aircraft most of his life. Thus, probably also never dove, and would not have thought going on pure O2 as a problem because it was a common practice in higher altitude unpressurized aircraft. Have to think he didn't know that or he would have written a suitable air mix in his novels.