Sorry to reply to an old post, but I was going through some of the questline articles and was curious about this point. As far as I know, the Highborne were responsible for moving the Bell to Darnassus; Dalaran resources were not used. Jaina personally assisted in securing the Bell once it was in Darnassus, but that wasn't using Dalaran. Earlier in the questline, Jaina had said that the Sunreavers shouldn't be forced to cut ties with the Horde despite pressures from both Varian and Anduin to that effect (why Varian wanted her to kick all the Sunreavers out and then later yelled at her for doing it seems contradictory, but I didn't write the questline), so likewise she shouldn't be expected to cut ties with the Alliance. Aethas and Rommath were helping Garrosh identify mogu artifacts before Jaina was assisting Darnassus, and that likewise was not considered a broach of Dalaran's neutrality. It was only when Dalaran resources were used for supporting one faction that a broach of neutrality was brought up.
Just to be clear: I'm not saying Jaina is in the right with the purge. The portal leading to a group of Sunreavers is pretty damning evidence but far from conclusive; it definitely did not merit instantly attacking the Sunreavers standing guard.