Yes, he could, with some caveats. One is that the vials are very expensive at 24 points, given how rare and powerful they are, and each vial only has one use. The other is that given Xenk's unique situation, the vial would not be a permanent fix, and the curse would come back after two to three months. (The details of which would be up to you.)

However, there are rumors of an artifact that might provide more lasting help. But it would require a bit of questing on Xenk's part, if you're interested.