You say you are not approving of homosexuality...well yes thenagel, you are. And your son will see this.
Yes! His son will see that his father does not presume to judge other people. He can love and accept people for whom they are. He doesnt have to agree with it, but he is not correct to condemn and cast stones either.
Let me ask you a question- if your son came to you and told you he was gay, would you kick him out of the house? Disown him?