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...