No idea. I’m happy with the Cooper and Quinn hypothesis. Or it could just be some crazy thing cooked up his sick head. The guy was severely mentally ill.
I think it is a simple mixed metaphor. The word Ishmael and AX are only vaguely found together in a Islamic quote, but the quote does not seem to mesh with this guy's thinking. There is nothing at all Islamic in his thinking. So, I think he read the Quinn books, and took Ishmael from that, and the AX is another metaphor for a couple more possibilities...
I'm thinking Alpha and Omega as "A" and "X" are the first and last letters of the alphabet, and also as a mis-spelled Axe, as a weapon of destruction.