great job! You definitely have kiruv talent and should pursue it. Seriously.
(Next time, maybe tell him that being that you enjoyed the conversation with him and he enjoyed it too – he said he likes your logic – he should join you for a shabbos meal. Not because he should believe in shabbos but just because it will be enjoyable, and he will make your day by coming, just as he made the kid’s day by shaking the lulav).