Sad that you tried a "trick" to get your money, all you needed to do was to tell the truth. Your correspondence with the seller would have proven that he didn't send the merchandise to the address you requested. The TXID is empirical evidence of the actual facts of the matter.
Actually I didn't have the 'tell the truth' option:
Picking 'Item dispute' here wasn't possible. I can only paraphrase the error message that was given, as trying to reproducing it now gives me another error message because I already filed a dispute for this transaction and my claim was rejected (I can't do it again). The initial error message was something like "this transaction is not eligible for buyer protection". My understanding is that when you choose "family & friends" type of transaction, you can't dispute it, at least not this way.
So the only option left was the second one i.e. unauthorized transaction. This forces you to imply that your account was hacked, to change password etc. I did mention, in the description field, that it wasn't the case and that instead, the receiving account wasn't legit, i.e. Timothy White is not a real person / is a fake identity. It didn't help.
Nevertheless, it looks like you still have not issued negative feedback. If it's true that he didn't have neg feedback before you dealt with him and now he has lots of negative feedback perhaps some of them would have been warned if you issued him neg fb when you realized you were scammed.
Your point about giving negative feedback ASAP to protect others is valid. That being said, the scammer used delaying tactics. There was an unfortunate coincidence: scammer pretended that his account was frozen immediately after I sent him the money, because of suspicious activity. At the very same time, I noticed that the credit card that I used for the transaction was blocked by my bank for real (I still don't know why, probably automatic anti-fraud algorithms / patterns). This gave some credibility to his claim.
If you look closely at his trust reports, you will notice that his scamming activity was very short, from 2015-02-16 to 2015-02-19, i.e. 3 days. Lifting the blocking of my credit card and sorting things out took me just about the same time, so it was a bit too late already.
His account was created on November 19, 2013 and a quick review of his posting activity at that time didn't make it suspicious, although by now I would suspect that the account was only bought recently by the scammer. This is why I don't like the forum policy of 'officially' allowing account resale, although I'm aware that prohibiting it by the rules couldn't prevent it entirely.
My point here wasn't to complain about it, otherwise I would have done it in scam accusations. I take responsibility for getting scammed because I didn't protect myself enough, it was a risk that I was willing to take at the moment. My point was rather to ask how PayPal as family & friends payments can be charged back at PayPal level (i.e. not credit card charge back).