Action Stations doesn't prove anything in that regard, though - it was written many years after the war was over, so there was no need to cover up anything. On the other hand, we do know that Confed has at least at certain times tried to cover up its military situation, as is heavily implied throughout WC3 (both novel and game) and in SO1.
In the case of the McAuliffe ambush, it would have of course been a necessity to cover the whole thing up (not permanently - by '54, the truth seemed to be partially out, though Claw Marks still downplays the degree to which Confed failed to prepare for the attack). The Kilrathi couldn't be certain exactly how much damage they did to Confed's navy, so giving them the numbers (by broadcasting them in public channels) would have been potentially very dangerous if not suicidal.