Cancellations were not done to prevent crew members from getting to DCA. Cancellations were done on originating trips where there was either a c/o or f/o unable to be filled (or both). If there was a conspiracy to block flights into DCA, check with the pilots, they are the ones who sicked the pairings.
Nothing like evaporating lazy and otherwise useless speculation, cleansed with the napalm of truth.
Pilots calling in sick were not the problem, with not one base/aircraft/position experiencing over .5% sick calls. Most were zero or barely registerable.
However, I did notice that over the last three months, available reserve pilots for each day systemwide have settled in at, on average, much less than one, approaching .07%. While I did not check POTA (priority of trip assignment) as such data is not available to me, judging from my friends experiences (heresay), resource managements attempts to depend on POTA to staff flights have finally reached ridiculous levels and, perhaps, today, the blockholders just said, NO!