I for one thought that Udina just did his job, even if I thought he was making the grade as an A+ son of b****. In his position, I don't think he could have done much else but stop Shepard, before he got too out of hand on what the Council thought were unsubstantiated "dreams".
The more I think about it, had Udina actually supported Shepard in front of the Council (especially when they hinted for him to shut Shepard up), he might as well have lost his position and his influence with the Council, and the Normandy would have been impounded anyway; except now just by C-Sec instead of the Alliance.
Freeing the Normandy through Anderson knocking Udina's teeth out, and then using his computer in the Alliance embassy would have been impossible; it would have to be done at C-Sec headquarters or maybe Executor Pallin's office. Who knows how that might have turned out :/.
Plotwise, this was also the logical decision that Udina could have made; Bioware had already estabilished his political-savvy character, so it didn't much suprise me when he agreed with the Council. Maybe, this way, things turned out better off. Besides, I couldn't have seen my Shep backing down, especially against a half-assed stupid political game. Just my 2 cents