It was not a sick out. The article clearly states:

“The sick call rate over the weekend was no different than it has been since June and the pilots actually picked up open flying as well,” Amy Robinson, a spokesperson for SWAPA, told TPG on Monday.

But the whole point of a sick out is to send a message. I've never heard of a sick out that didn't at least have employees going "oh yeah I'm real 'sick' <wink wink>".