Linguist accounts are for the most part supervised by their organizations. They can be activated/deactivated automatically, but if they want to let their PMs know that they won't be able to accept the jobs for the next 3 days or a week, they have to do it externally. Having this feature incorporated within Phrase would improve the communication between Linguists and PMs as well as clarity.
Linguists are only able to inform PMs about their status externally.
Linguist can signal the unavailability for a certain period of time in Phrase directly (either by some status feature, or there is a calendar for linguists to fill out). Unavailable linguists cannot then be assigned jobs in that given timeframe.