I see, it was just an opinion not a fact (although you did state it as fact). You made an assumption about the OP based on your prejudice of people who use the word "guy". I just assumed he was talking about a bloke (there was a clue in the post as he referred to the person as "he"). I think it's well understood that guy refers to the singular male, I've never heard anyone call a girl a guy. "Guys" is different though and that is what (4) is referring to.Like I said it's an awful word, mostly used incorrectly. In my opinion, and that's what your questioning here, it's roots as a gender specific word are dubious and 1. 2. and 3.2. rule it out as a direct comparison to lad or bloke.
My hope and the reason I originally quoted the word was that it was being used as stated in 4.
To be fair, I don't like the word "guy" myself but I haven't got a problem with people who use it.