1) Is it permissible to label the Saudi king as munafiq?
2) Is It correct to label any deceased person as a munafiq who has passed away in our era?
1. We do not know him personally. So we are not in a position of commenting.
2. The munaafiq that refers to munaafiq i`tiqaadi was made known to Nabi (sallallahu alaihi wa sallam) alone, for Nabi (sallallahu alaihi wa sallam) used to receive wahi, and after Nabi (sallallahu alaihi wa sallam) the process of wahi has been permanently stopped. Hence how is it possible for us to to call anybody a munaafiq i`tiqaadi.
And Allah Ta’ala (الله تعالى) knows best.