It is possible to disagree with both actions; but it doesn't destroy "but you did it first" defense. The precedent[1] happened and was generally accepted, so unless you want to go the quod licet Iovi, non licet bovi route, it is supposed to be acceptable defense.
The principal way is to reject that defense for all cases, including the first one.
[1] And not just Morales' plane; this happened more often than that. Morales and Snowden were just high profile.
Yeah, the Snowden affaire should have been the impetus for a new convention on civil airspace. It would have been a good chance to also mop up some of the worst abuses post-9/11, and re-commit US and NATO to a respectful and democratic future. Sadly the chance was completely missed, even after the red rage for the leak had somewhat dissipated. And here we are.
I don't the think the thread was about defending Lukashenko's terrorist act, it was about reminding everyone that, shamefully, such acts are not limited to demented regimes like his.
We are all right to be outraged by what happened in Belarus. We should also be even more outraged when our own governments,which we nominally have some control over, do similar things.
The principal way is to reject that defense for all cases, including the first one.
[1] And not just Morales' plane; this happened more often than that. Morales and Snowden were just high profile.