Foxtrot,
The script does contain a flag (-o) that prevents the OUI lookup, which would skip the download. Additionally, it is a one time download from IEEE.
Hope that helps.
To help with wifi surveys and pentests, I have created a Python script that parses PineAP log files and displays some simple metrics; namely the most common SSIDs and average SSIDs per device. Read more about the functionality and grab the script at https://github.com/ginjabenjamin/SsidyMetrics