If anything, it would be better for supporting the value of the estate if so many creditors asked for a BTC payout that the trustee felt pressure to liquidate the fiat by converting it to BTC for payout.
I find it extremely unlikely that Kobayashi will buy bitcoins as a favor to creditors, to save them the work of buying BTC on their own. He will not buy EUR or USD to satisfy those who prefer those currencies; why would he do that for BTC? For one thing, if he were to get a bad deal while doing so, he would expose himself to lawsuits from the losing creditors.
Kobayashi is considering the possibility of distributing the BTC as BTC only because converting BTC to JPY would be a lot more work and risk than converting EUR and USD to JPY (which he will surely do). BTC payouts still require agreement from the court, however, since by law and tradition he would have to convert everything to JPY.
By the way, suppose that, by the September deadline, the approved claims times the reduction factor would require distributing (say) 6 billion yen (G¥), and the clients state that their prefernces are 3 G¥ in JPY and 3 G¥ in BTC. But the assets he has are 1 G¥ in JPY and 5 G¥ in BTC. What will he do? He cannot force users who want JPY to take BTC...
Good points - I agree that it is extremely unlikely that bitcoins might be bought. I think all or most other currencies have been converted to JPY by now. You may be right that Kobayashi will not buy EUR or USD, but if so that will be unfortunate for creditors. Most US banks will probably take a deposit in JPY, but they will need to convert it to USD and probably don't offer very favorable terms for this, with bad exchange rates and possibly additional fees. I agree that Kobayashi would not force users who request JPY to take BTC, but unfortunately he might force users who request BTC to take JPY (citing Japanese law to justify it).