yeah, that's the problem... both in the movies and in the show Coulson has been presented as almost supernaturally unflappable. So this particular explanation is tonally pretty damned flat for his character.
Does it work as an explanation? it does, ask anyone who's ever been caught up in an end-of-life debate about what is acceptable and it becomes both morose and complex... but... yeah, from a story-telling PoV, it just doesn't rise to the occasion. Though I will give ABC kudos for going ahead with showing a couple of pretty gorey scenes on prime time (read prior to 10pm) TV.