A few things to learn Nakukak. You need to harden up. Sticks and stones will go a long way.
Diablo is a predator, once he has drawn blood, and gotten a rise out of someone, he will continue to ride that till he decides to move on. Lots of people are like this, just not to the level diablo takes it. Who hasnt killed someone or beat someone in a game, and thought in thier head, "they are so pissed" and then you kill or beat them again, and it makes you laugh a little inside, wondering if they are freaking out FPS doug style. This is what diablo loves. He loves to be hated, and he loves to get people going, and frustrate people. If you dont react, he will most likely move on. He will still kill you when he sees you, but he wont actively hunt you, if he isnt getting the reaction he wants. So let him kill you when your out and about, let him dry loot you, and just regear, and move on. Dont try and do buybacks, or spam the forum. It just makes you a target.
As far as getting rid of him on siege, its almost been done before, though I dont think your pockets are deep enough. I forget who it was (speedy? SW?) but they paid 100k per new death screen shot, and a good chunk of change for his gear. It was locked down on display. Needless to say the thread was filled with kill screen shots, and his gear was stacking up in luna for all to see. Was a lot of deaths, and a lot of money changing hands, and locked down in suits. At the point he was quiting, the movement backed off. It was done to knock him down quiet a few pegs. And worked for a short time. Im sure with deep enough pockets, you could drive anyone from the shard. But thats also one less player.
Some will say that he drives players from the shard, this is only partly true. If he scams someone and they loose a lot, or everything, they may leave. If he PKs someone and does a welcome to siege speech, and then dry loots them, or res kills them, and they leave. Well I gotta be honest, they were not going to make it on siege anyway.