This young man obviously has a chip on his shoulder and, being new to the game, is determined to see the problem as the editor and not his own. He takes every rejection personally and is looking for reasons to blame everyone but himself. He's not willing to work or learn, as evidenced by his tone. He's young. He won't get published no matter how old he gets unless and until he begins to see the problem as his in fitting the submission qualifications and not the editors. It's a common failing and one I've seen many times before as an editor.

Sometimes the problem is the editor having a bad day and sometimes it's not a good fit. It's hard to have this level of involvement with every writer submitting a story and impossible to sustain. You did the right thing. He needs to learn. You do not have to be the one to teach him. He's not ready to listen.