I'm not going to be much help, but hopefully I can give you some light at the end of the tunnel. I have a Bachelor's degree in Computer Science, a Bachelor's degree in Mathematics, and a Master's degree in Computer Science, all very heavy math based studies. To this day, I have to think about simple multiplication. While reading your example of 8x6, I solved it by saying in my head 8x5 is 40 plus 8 is 48. I don't memorize well; I never have. Formulas, got it. Plain memorization for memorization sake, I struggle with (as my grades in subjects like History will attest).
Your son isn't a lost cause if he can't memorize those tables. Maybe doing like I did and learning the common ones and then the tricks for getting to the others might help? Like learning the 5 times tables, then you can add or subtract to get 4x and 6x.
Good luck!