I guess you have already taking your decision by blocking him..A middle aged man will probably be a married man and giving out gifts to teenager will sure raise eyebrows..you said you know his intention and because of that,you decided to do the needful.
You don't need any advice. You have already blocked him because you saw the signs he was trying to flirt with you.
Some people may just be nice though.They may not have bad intention. That's one reason why one need to look closely before taking her final decision.If you block such a nice person, then its your loss not his. You are the one that stand to gain from him
In a case where the man is sending romantic text messages or asking you to send your sexy pictures or nude pictures, or urging you to hang out with him in a hotel, then you don't need a soothsayer to tell you that he wants to tuck you in nicely.
At the end of the day,it all boils down to you and your decision. Watch out for signs..I believe any girl will definitely know when a guy is flirting with her. I guess you all have a sixth sense about this things.