Selling goods which are public is not allowed.
This is from your TOS :
6 Posts such as "good luck selling","nice product",etc are considered spam & will lead to warnings.
Since you don't warn people who say good luck with sales I tought that was the same about selling free things
Moreover, many combos sold on nulled are public
Since I didnt scam him because he didn't send anything, why would this result in a ban ?