I'm guessing you don't know that no matter what is set in options, / is always a command prefix.
  • if $left($1,1) !isin / $readini($mircini,text,commandchar) && ...


However, i am of the opinion that scripting for the obscure is unnecessary, the very few people who have a different commandchar should know they have set one, and so adjust such a script accordinglly.