Good morning.
You might want to change your title. It's Reverend Richard Grund, Jesse is the son who was engaged to KC at one time.
I think Mr. Grund has a vested interest in Caylee because at one point, he thought that she was his granddaughter, and had grown very close to her. From what I understand, KC and Caylee spent a lot of time at the Grund house when her and Jesse were engaged especially. I've seen pictures of them opening Christmas presents, etc.
I would think they became very close to Caylee during that time period. She was adorable and I don't see who couldn't. I think he also sees an injustice being done to Caylee and feels the need to defend her. His son has also been implicated by CA and was blamed at one point for Caylee being missing. I can certainly understand why he has a vested interest in this case. He was pretty much unheard from until CA blamed Jesse and then he felt the need to defend his family.
Anyone who is willing to be a voice for Caylee is speaking up and because he had loved Caylee like she was his own granddaughter, he feels very passionate about this.