@Beatrix W The computers will get their own locale except for those that are not getting updates. But those who don't get updates that remain on the PST locale will get the incorrect UTC delta.
Consider that today a computer in California will get a UTC difference of -7.
But in November, assuming California has implemented always-on DST (still unknown when it will be implemented despite voter approval), a computer that has not been updated will fall back an hour.
The user may realize events are an hour late because of the time change that no longer occurs in California and will then manually change the system clock to compensate. But the locale rules of a computer that has not been updated will return a UTC difference of -8 when it still should be -7 and my application will still trigger events one hour late if I base the triggers on UTC time instead of local time.
I should mention that this application caters to the farming industry and interfaces with field hardware. Many of my users will not have internet access to update their OS, update the application, or contact a time server.
I greatly appreciate everyone's thoughtful suggestions!