...or thought it was worth their time, or wanted to be associated with such a program in any way.
While no other experts gave an opinion on that handwriting as far as you're aware, consider all the people who have expert knowledge that Elvis died on August 16, 1977. I'm talking about unbiased people without motives who haven't appeared on a TV program, but were involved in his autopsy. Then there are those who were at Graceland when he was found, the EMTs who tried to resuscitate him and transported him to the hospital, those who worked on him there, the coroner, those who prepared his body for viewing, etc.
While that sounds like a different subject, it's not. Any claims from an expert--even if the guy is respected in his field--which depend upon Elvis not having died on August 16, 1977 in order to possibly be true, are not deserving of any serious consideration, regardless of how legitimate he or his findings might seem to be.
Let's keep this friendly.