At one point he WAS related to Caylee...when Casey led them all to believe that Caylee was Jesse's child. They were engaged, she spent alot of family time with them, and they were Caylee's caregivers on many occasions. Until the DNA proved otherwise, they were family in thier minds and hearts.
With that said, anyone who has had any history with Casey can very well shed some light on this case in some shape or form.
IMO, I don't care what forum it may be in, let them talk if it brings closure to this case.