I dont think Bing nuked it on purpose. It looks like for the cyber monday query Bing is placing more emphasis on date sensitive information. Target and Dell are the only shopping locales to rank organically and they both have date sensitive info. Target places the year in the title and Dell has lots of dates in the fine print below that correlate to this years cyber monday. The rest of the rankings are news publications listing deals etc...
Bing does slip in Bing.com/shopping but it is below where cybermonday.com would typically be.
contrast this with google. In google history seems to play a larger role than date stamping because cybermonday.com is #1 and wikipedia is #2. we could also say that keywords in the root domain are playing a large role in google rankings for this phrase as there are 5/10 page 1 results with 'cyber monday' in the root.
3 of the 10 results are stores in Google and only 1 is a news website. i think that shows us what the two are looking at for this holiday ranking term and I dont think it correlates well to drops last week in Bing.