Of course. 2FM and 3JRF bit off more than they could chew. Going after a Tev destroyer with it's comm systems intact as if they'd see it as an acceptable loss? They didn't follow one of the golden rules and they paid the price for it. If something seems too good to be true, then it probably is.
Think about if they had left the Carthage drifting in orbit of Saturn. It would've been out of action for weeks most likely, depending on how extensive the damage was. Not worth going in for the kill.
The Carthage jumped out of the last "engagement", if you can really call it that, before she could take much damage. When it arrived at Saturn, all that was needed to bring her back into the fight was driving her out of Saturns gravity or a quick fix of the engines at most. She would have been out of the war for hours maybe a full day tops.
And because they couldn't get the comms before the attack, they tried to make sure that every ships that might support the Carthage is busy with defending against the other attacks.
Delenda Est was NOT a small engagement of only those four Karunas and their Sanctus escorts. It was a massive fleet action that involved attacks on multiple high-priority targets.