It looks like a formation for transit rather than an attack formation; if they were trying to disable the gate, they (well, if they were you) wouldn't have stuck together that way, they would have come in from different angles.
There is no evidence that they can use the jumpgate other than their formation; they didn't send a jumpgate signal during the combat, but they weren't to the standard amount of closeness to do so, either. If they're the same guys as were in the Tarn Alliance, they ought to be familiar with jump gates, though, as there's the one in Craterrock supposed to go there, and the inworld jump gates date back to the Alliance.
It looks to you like they went until it became clear that their plan wasn't working, and then they punted entirely, rather than go to a new plan or even make modifications to the plan as it stood. They are unlikely to return with the same plan; you would guess that whatever new plan they come up with, they'll be moderately strongly optimized for that (i.e. redliners and yellowliners are built for the "disable and sterilize" plan they used both times) - this suggests that there may be something of a breather while they retool their fleet for the new plan, whatever it turns out to be.