It is just possible that this guy is in love with you. That’s why he wants to emulate you, he wants his life to have you in it….that explains the sons clothes.
Obviously you don’t feel the same. But I think the heartlessness of some of these suggestions is appalling. If you can’t bring yourself to say to him that the relationship is getting too intense too quickly for you , and you would like to take a pause for a while, put it in a letter, or even an email. That’s courtesy and consideration for someone else’s feelings.
You don’t have to love the guy, you don’t have to see him , but I think you can be polite and have some thought for his feelings, just as you want him to respect yours. The suggestion that ‘you owe him nothing’ is bizarre, it makes him sound as if he broke in through a basement window and assaulted you: you have met his son, for heavens sake. He’s not some random cat caller. You owe him some courtesy, just not the rest of your life.
By the way, if he is a sinister stalker, you would be better off in the short term being polite, because you may be able to defuse any potential fallout.
Putting his stuff on the doorstep is a dreadful idea. Presumably you invited him to bring it to your house,,or at least consented. Shoving it outside to get dirty or stolen is a complete over reaction., and the best way to provoke trouble.