I agree that the cover up was what made this of such consequence in the escalation of the troubles.
It was likely done in the hope of reducing the impact. A hugely costly mistake.

Big Mick, members of this small unit killed indiscriminately, and shame on them, but please remember that small units of your army have done much worse things than Bloody Sunday.
In Iraq for instance I recall reprisal killings of innocent unarmed civillians including children, and a whole family killed to facilitate the rape of a young girl.