In one way, yes. I can see the Army's/BP's perspective.
But if I was a relative? I would not be interested in a coverup, no matter what agency we'd be talking about. I wouldn't shut up about it. Government agencies don't get to cover up the fatal mistakes they made, absent a VERY good reason. Like, a reason that's compelling to the taxpayers, not the institutions nor the families.
The Tillman shooter has been living with the guilt for almost 20 years now. And everyone who wants to find out knows just who he is. He probably adds his own salt to the wound every day. Honesty is the better policy.