Just an update to my previous post:
Wrote in to UA and they confirmed that indeed, p.s. flights are BF and that a customer whose BF leg isn't upgraded will get their GPU/RPU redeposited.

Here's the text of the email in its entirety (names redacted, natch).
"Dear Mr. Matkus:
Thank you for contacting United Airlines.
Premium service flights offer BusinessFirst. The GPU will be
re-deposited if the United BusinessFirst or United GlobalFirst segment
could not be upgraded.
We appreciate your business and look forward to welcoming you on board a
future United Airlines flight.
Regards,
United Airlines"
Originally Posted by
Kacee
ps is not yet sold as a BF route. So if I were you I would call and have the GPUs applied only to the transcon segments. You can then apply them to the PSP-LAX segments if/when the transcon clears.