Are we talking about the domain Lilac.com owned by Elliot Silver, or is that just an example domain?
Regardless, Lilac is a generic term used by many companies, people, organizations, etc.
You can't just file a trademark and have exclusive use over the generic term and claim superior rights. That is not how it works.
If you file a UDRP you can expect to be hit with a reverse domain hijacking finding as well as potential monetary damages if the owner decides to purse it in a real court.
Brad