He is helping his parents to do Hajj and he has not yet done Hajj himself
Hajj is obligatory for every Muslim who is free, of sound mind, an adult and is able to do it, once in a lifetime. Honouring one's parents and helping them to do things that are obligatory is something that is prescribed in sharee’ah to the extent that one is able to do it. But you should do Hajj yourself first, then help your parents, if it is not easy to do both. If you give precedence to your parents over yourself, their Hajj will still be valid.
And Allaah is the Source of strength.