Yes, this man is very smart, and knows a lot about religion. Anything that he says or suggests if going to be backed by a good reason, and should be followed by the people who practice this religion. He will help to lead a religion to an era of prosperity.
Given that L. Ron Hubbard is most known for his works of fiction and his founding of the Church of Scientology, I doubt it would be suitable to use his quotes for inclusion in a Muslim homily. I do not believe L. Ron Hubbard has any quotes that would rightfully fit into this use.
Hubbard was a science fiction writer - that is all. The fact that Hubbard started a cult that was a widely adopted (at least, in relation to many other cults that are founded) does not make him a theologian or brilliant theological thinker, and his quotes shouldn't be taken as such.
L. Ron Hubbard was a science fiction writer who was known for his science fiction and fantasy novels. He is not associated with the major religions, excluding Scientology, which he founded and many consider more of a cult than a recognized religion. An L. Ron Hubbard quote would not fit the mold of most Muslim practices.
L. Ron Hubbard decided to start his own movement which later became Scientology mostly to further his own reputation and power. He has no place being quoted in any homily for a traditional religion unless it is to point out something that compares or contrasts because he is not a religious or even a spiritual leader.