The referrer check is just on
https://my.usfirst.org/myarea URLs. The
https://my.usfirst.org/frc/scoring URLs are used by FMS to download team lists when setting up at an event. They're tab-separated tables, so they're easier to parse but uglier to look at which is why I implemented the hack in FRCLinks instead of redirecting to them.
You can get the event IDs by looking at the list of all events:
https://my.usfirst.org/frc/scoring/index.lasso
I'm guessing there's no referrer check on them because then FMS would have had to add that header in its data download requests.