Who are "they?" Did they view TA's body in person? Did they have access to all the reports, tests, investigator's notes, etc, etc? There isn't a question about which wound was the first fatal one--we already know it was the neck wound. The big debate is if TA was shot before that neck wound or after.
To me it doesn't matter because either way the case is 1st degree murder and eligible for the DP. To me it's a completely moot point simply because it doesn't change the outcome of the case, it doesn't change the charges, it doesn't change the potential sentence criteria, and TA is still dead regardless of which order the wounds occurred.
However, to many it apparently does matter very much--it appears to matter enough to debate it for thousands of posts, though no one can determine the correct answer from the numerous lay opinions expressed and for whatever reason the expert ME opinion (of Dr. Horn) is simply not trusted or believed (by some).