Glenn Greenwald is largely right.
These facile attitudes toward 'teaching people a lesson' are an enemy to the peace and to peacemakers, quite often.
To my mind, it feeds a consequentialist, fatalistic or contractualist view of history: if they do this, then we are justified to do that - oh well, their choice.
Such an attitude is fed by assumptions that rhetoric is reality; largely inert missile fire from "territories" is "war"; or that obvious and necessary restrictions, a.k.a. "blockade", are "occupation". It blots out the shades of gray, the area in which moderate political voices need to assert themselves.
One can observe that, without making a derogatory opinion about the balance between Hamas' political goals and Israeli political goals (or motivations). This cannot be emphasized enough - one can find a reasonably just cause prosecuted unjustly, right? (Or just stupidly).
The situation requires maximal finesse, arguably, not more brutalization. Certainly, exchanging terror for terror is no answer, just an invitation to fight to the death outside the gates of hell...