Why is Boy spending his holiday time with the head of the worldwide Muslim Ismailis?

Why is this billionaire's Aga Khan museum in Toronto tax exempt? It was privately funded. Our family has received countless full colour flyers advertising the Aga Khan museum, yet he claims it is a 'place of worship'. We are not Muslim.

Ismailis are required to give 5 – 12% of their annual income to the Aga Khan. He is the top breeder of thoroughbred horses in France, owns a bank in Pakistan, plantations in Kenya, and a chain of luxury hotels together with his private jet and massive walled estate in Chantilly, France – making his personal wealth estimated at over $15 billion.

Yet, he doesn't want to pay taxes on his Aga Khan 'museum' and 'place of worship' in Toronto. 

And he invites Boy & family to spend private time with him on his private island. And Boy accepts. Quietly and secretly.