The CARB EO number (D-269-86) for that part number checks out for use on a '19 or '20 VT, so as long as the smog station is legit you won't have any issues. As for why that site says "not legal for use on...", no idea - maybe the site is cross-referencing to the wrong model year or engine or something.
CARB EO D-269-86
Edited to add: make sure you actually have a '19 or '20 though, since those are the only years that have a CARB EO for that part number. If you have a '21, you'll fail. I went through this on my Gen1 VT - a lot of the intakes available only had EOs that were valid for '13 and '14 VTs, so they wouldn't pass on my '15. Took quite a bit of research to find my AEM and make sure its EO was valid for my '15 model year.
CARB EO D-269-86
Edited to add: make sure you actually have a '19 or '20 though, since those are the only years that have a CARB EO for that part number. If you have a '21, you'll fail. I went through this on my Gen1 VT - a lot of the intakes available only had EOs that were valid for '13 and '14 VTs, so they wouldn't pass on my '15. Took quite a bit of research to find my AEM and make sure its EO was valid for my '15 model year.