What's lacking from your story is your margin situation at the time of IB's action after that "other" assignment.However, on Friday, (I am in Australia), the last time I could check my account was 2 hours before Friday's market opens. When I next check the account about 3pm Friday (New York time), IB have fire-sold all the gold stocks and gold stock options because of another assignment.
If you received liquidation notification from IB due to insufficient margin and you did nothing, how is this their fault?Disregarding, for the moment all the circumstances which got me into this position in the first place, which I take responsibility for, I still find IB's action draconian, unnecessary and to put it mildly, a big f-you from IB. Even their warning emails about the liquidation threat (unlike any other IB emails) are going straight into the Junk Email bin of Windows Mail because they are so roughly formatted.
If you had sufficient margin to cover your positions then you may have a legitimate complain against. If not, no broker will let you coast fly by a margin call w/o dealing with it.