They may exempt the person from Biometrics and make a refund later. I didn't see this in any online document, and I don't know how they decide it (if depends of the officer that analyses your application as well). But I also got AOR without Biometrics (January), and after I got GCMS notes in May I noticed this situation. Some small screenshots:
https://ibb.co/KW8sXx5
https://ibb.co/Cb4GfmQ
I believe, as well, if the person already did biometrics (in previous applications) and it is still valid, they can also have the same procedure (exempt, refund).