It has occurred to me that Vulcan must have some form of sex industry to handle those going through Pon Farr who aren’t currently married or otherwise involved. Otherwise, they’d have constant issues with violence from those suffering the “blood fever” whose spouse was far away, or had died, or for some other reason had no one to mate with.
Given Vulcan attitudes towards sex, it’s probably kept out of sight, and is only “officially” available to those experiencing their “Seven Year Itch,” but it has to exist, right?
In this case, at least, it was less a cure, and more temporarily offloading it to someone else to deal with. Basically the equivalent of Lwaxana affecting the entire Enterprise when she was going through The Phase, or someone with an injured leg leaning on another person to use as a crutch. Except that Sarek was relying on Picard’s emotional processing capabilities.
Presumably his symptoms would return when he ended the psychic connection.