A title, by itself, is insufficient to sustain a copyright
lawsuit. However, if the author is using (or intends, within 12 months) to use the name in commerce to market the book, then the author may be able to register the name as a trademark
, and even if not, may be able to make a "trade dress infringement" claim against the editor.
In particular 15 U.S.C. 1125(d)
provides the federal law that permits the owner of a "mark" (such as a book title used in commerce) to sue an infringer for a bad faith registration of an internet domain name (e.g., URL).
Re small claims court, California law only permits the "recovery of money" in a small claims action. So, while you could sue for up to the maximum $10,000 in damages, you cannot get an order from the small claims court to force defendant to cease using the infringing name. Sometimes a money judgment is sufficient negotiating leverage to obtain the release of the domain name. If not, then you would remain in your current position, and you would have to sue in California Superior Court or Federal District Court.
There is an alternate process for obtaining a resolution of a domain name dispute. The ICANN provides an explanation of how to file for an arbitrated resolution at this link.
This is the least costly means of forcing the removal of the editor's alleged infringing use. However, the process cannot be used to obtain money damages. So, it's sort of the inverse of a small claims action.
Those are the options. Please let me know if I can be of further assistance.