Or a chief pilot. In any event, if there are no contractual protections for line flying, and no line guarantees (one can't show harm if given a trip not on one's line, or removed from a trip, when one wouldn't break guarantee), then advocating calling in sick to avoid flying one doesn't want to do borders on a job action, and certianly could merit diciplinary action. As you note, a pattern may certainly warrant such. It's not only an HR matter, however.

If one calls in sick, an employer is quite justified in requiring a doctors note, both to verify the illness, and to show the pilot is fit to return. An employer who suspects the employee is lying, may very well make such a request. That may make such a game expensive, and presents jeopardy.

If that employee group were to be in negotiations, and negotiations were to be tense, allegations of calls for job actions, sick-outs, or other action that's not backed up by a CBA, would be damaging to that process. Particuarly such a call on a public forum. Counseling others to call in sick when they don't get what they want certainly lends credence to an allegation of job action, and in the least, may result in disciplinary action to those following that counsel. Either way, nothing good comes of the call or the fallout. The call loses its efficacy when advertised in advance. Such as here.