The account of what happened at Haditha on that day which was put out by the US authorities was completely false. That has been demonstrated beyond all doubt and this has been accepted by the US authorities. The individual identity of those who were responsible for that, directly or as instigators, is a matter where "innocent until proved guilty" is relevant. But there can be no doubt whatsoever about there having been a sustained attempt to deceive the world about what happened.

The assumption that "those involved would have brought it up" is very optimistic. The fact that convincing accounts of previously unreported atrocities against civilians - in Vietnam, and in colonial conflicts involving the British and the French, as well as in World War II and indeed in earlier wars - are still coming to light, after having been successfully airbrushed from our collective memory for all those years is a pretty strong indicator that ciover-ups do succeed in many cases.