Comment by tptacek
4. Indiscriminate attacks are prohibited. Indiscriminate attacks are:
(a) those which are not directed at a specific military objective;
(b) those which employ a method or means of combat which cannot be directed at a specific military objective; or
(c) those which employ a method or means of combat the effects of which cannot be limited as required by this Protocol;
So far as I can tell, this strike clears all those definitions. I think you may be reading 51(4) to be a prohibition on civilian casualties as collateral to military strikes, but that obviously can't be its meaning --- that would ban virtually all air strikes, for instance, and I'm pretty sure that isn't something the victors of WW2 were going for.
Am I misunderstanding the argument you're making? It's not unlikely that I could have!
You cannot specifically target a military objective using a small explosive in a crowded area. It’s not possible other than by pure luck, which negates any assumed specificity.