I don't really feel like parting with gold, sheep, or the time necessary to fetch them personally. But Anton would not be the one primarily doing the fighting here, so he will yield.
Yes, it was an unreasonable request by design, though not something which would have been impossible for you to fulfill, had you set your minds to it. Anyways, it is a minor setback, all in all.
I dunno whether the goblins would actually accept the sheep now, or that was just a thing the spectral knight told them to say. But Boudica would be willing to go get sheep in exchange for some of their trinkets of obvious historical significance.