Likely was fucking up his search engine results for his name and/or* online handle. This matters because a future employer finding out about your weird fetishes can really fuck you over in the Asian development scene.
My best guess is that Byuu wanted an exit strategy in case Nintendo ended up following through with a C&D/suit on his emulator project, but still wanted to be able to post his online username and detail his experience on a resume. And if his request gets rejected, he can destroy the farms and get it taken down either way - in his mind, he was in a no-lose situation.
*edited because I totally forgot that David wasn't doxed in the original thread, so it would have just been his handles
I believe that with one change.
Honestly Byuu is a crybaby pussy so I fully believed him when he said that he was upset about getting messages on Twitter all the time or his friends being dragged into it by association, and I think that's what would upset him more about search engines finding the thread when his handles were searched.
It just brings more eyes to information that he would rather they not see just in case they did decide to seek him out, or simply post where he goes and might see it, and say "lol byuus a furfag pedo" and he's read it and think about it all day.
He's emotionally fragile enough that I think that idea bothers him more than any employer finding it. How many degenerate coders [all coders] still get jobs just because of their skillset after all? Plenty more than someone looking for a public facing, PR type jobs.
Like Dyn said the fixation on deleting the thread was probably the end of it. He didn't like lying awake at night with tears in his eyes thinking people were reading unflattering things about him, which I'm sure he did often.
IIRC Null even tried pointing out to Byuu in the emails that the information in the thread was largely tame so he didn't get the obsession, and he said something along the lines of "I know but I can't help it I'm just weak like that I guess I just don't like it" didn't he?
Mommy, they call me names, I want to kill myself.
edit:
Japanese companies that "disappear" battered wives wouldn't touch a foreigner with a bargepole.
They'd have to forge residence cards and even passports for a non Japanese person.
Plus, if on a visa, which he was, as he'd not been in the country long enough to apply for permanent residence or citizenship, he'd still need to register at immigration every time his visa expired, japanese immigration offices have holding cells in the building and he'd be locked the fuck up in minutes and deported soon after.
Do they get forged cards though?
The business is entirely legal in Japan from what I read, so forging information for even native Japanese would make the business illegal and they wouldn't be allowed to publicly operate, as they do.
As I understand it your old identity isn't erased, you just go through intermediaries and get legal changes done and privacy laws are such that you can still use your information without it being flagged like someone who goes missing in the US being found by ATM withdraws.
The disappearing seems less like assuming a forged identity than it is just leaving when no one saw you and having the company and laws help conceal your action.
Immigration would still know him as David Kirk Ginder and he'd still have his responsibilities there and risk of deportation if he fails them. But they couldn't tell Nintendo if they came asking where he is or even if he's still in the country. Or the police unless a crime is being investigated.
It isn't used to escape the government at large, just make you hard to trace for anyone not exempt from the privacy protection laws.