Upvote:6
Security checkers have a lot of discretion here. I've had my girlfriend board a flight where she was identified as "Mr. Vo", and I've had my name abbreviated to just a first initial. Both times I successfully boarded the plane. They care much more about a valid passport with a matching photo.
Especially if they're flying from India, where not having a surname is a common occurrence, I think they should be fine.