Wonder if they were using transmissions on those frequencies as part of their on-site "Public Address System," as referenced in this 2019 SOP document (Section 8.4, page 26):
https://www.soundingrocket.org/uploads/9/0/6/4/9064598/sa_cup_irec_range_standard_operating_procedures_20190603__baseline_.pdf8.4 CELLULAR COMMUNICATIONS
While on the Spaceport, participants at the Spaceport America Cup should plan on experiencing degraded cellular
telephone network reception – or none at all. Limited testing indicates only Verizon Wireless customers may receive
usable service within the VLA. Participants are highly encouraged to bring their own handheld radios to coordinate
their operations. Similarly, participants are highly encouraged to bring their own portable FM radios, which will
receive general announcements broadcast over the Public Address System in addition to the Giant Voice speakers.