I guess a working theory is this: Withdrawals were starting to get very close to, or even exceed, deposits. To preserve his profits and try to keep going a bit longer, he reduced the interest rate, figuring this would reduce the withdrawals without significantly reducing deposits. Instead, this backfired, either increasing withdrawals, reducing deposits, or both. This forced him to shut down his operation earlier than he had planned to, so he needs time to wind down all his positions so that he can run with them.
Yes, I also believe this is the most likely process. I predicted it on August 15th already, which makes me wonder why he could not predict it himself. But perhaps he did, and it was just a gamble.
Nonetheless the wind-down procedure can easily take more time than anybody expected, so it shouldn't surprise us that he is trying to play for time. It doesn't seem to work very well though. The first noisy "WHERE ARE MY BITCOINS?" thread is already gathering comments, and there will be more.