This rumor was "validated" by the All Music Guide (which published it) as well as Amazon.com and StarPulse.com. Although I had previously tried to contact Varese in order to ascertain if this was indeed true, I had no success, as Varese would not answer my emails. While researching the Complete John Wayne Discography for this website, I tried one more time to contact Varese before adding this soundtrack to the discography.
Finally, they did answer my request for information, and Varese has confirmed that they have never released a complete soundtrack recording of the score for The Shootist. The only legitimate release of any music from The Shootist was on the Varese Sarabande release of "The Digital Premiere Recordings of the Films of John Wayne" (Volume Two), which is noted in the discography here: http://dukefanclub.weebly.com/10/post/2013/02/digital-premiere-recordings-from-the-films-of-john-wayne.html.
I apologize for any inconvenience this may have caused.