Instant upgrades on Y/B fares (a) require PZ space to be available, or PN if 1K or above and (b) do not apply to non-status travelers, so she's not eligible anyway. Furthermore, in many cases Y/B fares are substantially more expensive than the cheapest economy fare and often more expensive than first class. I sincerely doubt that the booking guidance for her company is "any economy fare is fine," as opposed to "the least expensive fare on a sensible routing."

UA will happily sell her an upgrade after ticketing.