Phylas was the name of more than one character, including a king of the Thesprotians who seduced Pylas' daughter Astyoche (or Astydamia), a king of the Dryopes of Mount Parnassus, and the father of Polymele (who may be the same as one or other of the first two here).
Whoever he was, Phylas has a name that means 'guardian', as for Phylacus. This could be merely a generally descriptive name for a king or a desirable name for anyone.