I suspect that the "as of" date was given for one of two reasons.
1. The distribution was done to various parties on different dates. 2. They realized that they forgot to make a filing or intentionally delayed a filing. Their lawyers just told them to say that they were distributed "as of" rather than indicate when they were actually distributed.
A seller or two showed up in early December and the selling intensified in mid December. I suspect that we now know who the sellers were. Also, the seller has been gone the past two days. I suspect the timing isn't a coincidence.
Also, someone might of started shorting their shares knowing that they could cover with the shares they would ultimately receive.