A&E's decision not to air the two interviews with Kyle's mother regarding his death, doesn't make the evidence indicating a possible cover-up or foul play less plausible.
Fortunately according to Victoria, the FBI is interested enough to pursue the matter.
In answer to Alanzo's original question, Mike Rinder himself admitted in a recent post on his blog:
"Our work is not done yet. Unfortunately sponsored television has limitations. There are things we cannot film or show on camera because of certain restrictions. These restrictions have limited us in many ways to tell the full story and in some cases, not permitted us to tell the story at all."
While we may never know (due to the NDA's) the reason A&E decided not to air Victoria's story, at least the FBI is looking into it.