A9. From the outset of the bankruptcy proceedings, we informed all relevant parties that we were going to sell BTC and BCH at the appropriate time. We discussed this with the Tokyo District Court and decided when we should sell them. Some creditors were of the opinion that we should sell BTC and BCH soon. We believe that obtaining a lot of funds made it possible for us to take the measures taken to ensure the benefits of the bankruptcy creditors.
I wonder who
all relevant parties are, is there a list?
As a creditor I don't remember being asked my opinion if it was appropriate to crash the market. Was it in my benefit as a bankruptcy creditor? No.
Who decided on
how to sell these BTC and BCH, why not use an OTC transaction?
I certainly don't feel like a "relevant party", but as screwed party. But we should be aware that he could have screwed us much harder.

About his decision to market dump, Jesse Powell wrote this:
For the record, Kraken was asked many months ago for advice on how to sell a large block of coins. Our answer was:
1. don't sell coins
2. If you have to, do it with an auction, which Kraken can facilitate
3. If you want to do it more privately, let Kraken's OTC desk broker it for you
We were explicit about not dumping a large amount of coins on the market. Unfortunately, it looks like the trustee made their own decision or was taking advice from elsewhere -- maybe whatever exchange they dumped those coins on. We had zero knowledge of these sales happening until it was announced at the recent creditors' meeting. Unfortunately, we have no visibility in to where, how or why the trustee sold those coins, nor whether any precautions were taken to prevent front running or self-dealing. Hopefully, the trustee will make it clear what their process was and put the questions to rest.
https://www.reddit.com/r/mtgoxinsolvency/comments/82ykgu/re_the_dumpening/