It’s airlines normal duties to check TRV visa holders document cz if CBSA have to return more than 5 passengers or more than 5 passengers file asylum from 1 vessel means flight . Huge fine & penalties imposed on airline . I am totally agree these check in agents are miss handling all these duties cz of this matter.
If all this happened to him he can file direct complaint with airline & DGCA ( department who monitor airlines in India ) . DGCA always take all complaints very seriously & action will be taken for sure if necessary