Why is that ironic?
Do you mean the irony of being glad that a dues paying member was driven from his job by the hooliganism of the union crazies? If so, I agree with you. This union "brotherhood" stuff is just a lot of rhetorical class warfare cloaking of darker forces at work, namely POWER OVER OTHERS.
You probably don't know this because you're probably not familiar with the workings of what went down with the SWA - AirTran acquisition and subsequent SLI agreement.
It's ironic because PCL is the biggest and loudest baseball-bat-waving, ALPA-is-always-right, "union-hooliganism"-supporting, self-proclaimed "union thug" on this board; and he's chiding you for talking about quitting the job if things don't go your way and there's a strike at your company. You'd have incurred the wrath of the rest of the pilots, and basically be assisting in what they wanted by quitting, hence the "mission accomplished."
After the spectacular failure of the SWA-AirTran SLI to be resolved in the way the AirTran ALPA MEC believed it would or should, PCL and others in that union incurred a lot of wrath on themselves for what happened (PCL is even widely believed to be named personally in an ongoing lawsuit), and as a result of the merger, PCL is talking about quitting the job because things didn't go his way. And surely the faction that called for his head will believe that his quitting will also be "mission accomplished."
Hence, observable and palpable irony for onlookers.
Bubba