I am all for Sanji getting COC but this is the most useless reason people use to say Sanji gets COC. Being royalty has nothing to do with getting COC whatsoever. Judge himself isn't a COC user, what makes you think being his son qualifies Sanji as a potential COC user?
Sanji Son of Germa King Judge who conquered North Blue the same place Doflamingo(COC User) lived
Both Kings
Don Chinjao Commander of all his army and have COC
Sai will have COC to thanks Don Chinjao
is only naturel Sanji to have it