Mike, thanks for your thoughtful analysis.
Indeed it seems that delays caused by sequester would be excluded from many policies. Some policies explicitly include delays due to strikes, but also exclude delays due to strikes which had already been announced/expected when the insurance was purchased.
I'm not sure that "cancel for any reason" insurance would work, since it covers exactly what it says... cancellation of the trip to return him. If I was delayed and needed to spend money to catch up with the cruise, it looks like that would not be covered.