Resposibility breeds maturity.

Lend him the deposit.
Write up a contract between the two of you that serves you both for the future return of your money.
He gets the mortgage and takes on the responsibility to the bank that wants to deal with him.
He buys the house.
He is eligible to claim the FHOG from his government

The house is then his.
He has the responsibility to really learn and make it work. He will see the numbers as they reveal the real benefits of property.

Doing is where we learn.
Make it Real.
Do business with him holding the vision of the fantastic man and investor he will be very soon.
Know inside yourself that you facilitated this, while realising that it is He who will make of himself what he will.

Responsibilty is the key in my experience.