Granted, his brothers might have given them just cause. But it was still an inconvenience, being unable to enter the complex, and while the Angel Castiel knew he should have been above stinging at having put everything on the line for these particular 'mudmonkeys' only to be cast aside, because reciprocal sacrifice was not the point of their association, 'Cas' - the creature he feared he was becoming - had fewer compunctions. Still, he waved dismissively. It was of little import.
While they were certainly worse places to start than addressing the issue of his brother's pet demon that, too, was not top priority.
"As always you are concerned with too small a picture." Cas stopped and turned to face Dean. "She is just one demon. I think we should talk about Sam"