Yes sure, but that is hardly the situation of that mission.
It wasn't the UEF (or in your scenario the russians) who called the truth. It was a single ship that went into truce with a single other ship and due to the jamming, neither high command was aware of that truce.
And the Arethusa returning fire wasn't helping either. Sure it's only a natural reaction to return fire, when you get shot, but if they had not shot back, the Nara might have reacted to the Indus' and Presedgets called to cease fire.
It was all a very unfortunate chain of events, where half of the thigns that could have gone wrong, did go wrong. With hindsight it's easy to point out what they could have done differently, but I in the situations they were in, the decisions of everyone do make sense, which makes it all the more tragic.
I personally came away from that mission enraged at the UEF - I am not objective in the least, but I am human.
If someone who 'witnessed' the mission 'first hand' can see the situation that way, it can certainly be portrayed even more badly for the UEF.
So because of the mistake of a single person (the captain of the Narayana) you hate the entire UEF?
But can you really blame him. The Indus wsn't authorized to initiate a cease fire with GTA ships and whenever GTVA ships came in contact with UEF ships, they tried their best to blow the **** out of them without mercy and often enough without warning too.
When you see someone who tried to kill you several times, do you take the time to check wether he aiming a weapon at you, before you attack?