Hence what I said earlier and what (I think) others previously have noted in the thread: as far as I'm aware, Indiegogo does not offer an actual cancellation option on a flexible funding campaign once the first contribution is received. Assuming that's correct, there is in fact no actual way they can close the indiegogo campaign short of ZUN filing a DMCA claim and having indiegogo forcefully remove it; presumably this would be the case because with a flexible funding campaign, the money is delivered much quicker, whereas with a fixed funding campaign the money is delivered only at the end of the campaign and only if the funding goal was achieved (otherwise, no money changes hands).
tl;dr this is a hell of a catch-22 situation they got themselves into (and continue to dig deeper), I'm not really seeing any way they can fully comply with both sets of guidelines binding them here at the same time. To be clear, though, that is entirely their fault for going into this mess headfirst without doing adequate research; honestly, if I were in their position (and assuming what I said above were true), I'd probably politely contact Oyamada-san (through someone capable of speaking fluent enough Japanese to conduct such affairs), explain the problem above with regard to the campaign, that it cannot be voluntarily canceled due to IGG's own guidelines, and ask him for guidance, possibly even raising the suggestion of just filing a DMCA notice on the campaign itself (which, in theory, _should_ force all the money to get refunded). But the bottom line here pretty much is that as I understand it, he cannot 100% comply with both guidelines in play, and it's fairly obvious which one he has to violate (and unfortunately it's the one capable of getting him sued).
One of the most frustrating things about this whole situation to me (as a relatively uninvolved bystander) is just trying to explain the levels of culture clash in play here, because most of my friends aware of the situation are effectively "secondaries" (for all that I hate to use that term) and don't really understand what the fuss is about.