Because stanton can't be bothered to let us know:https://bluray-disc.de/blu-ray-us-importe/177861-once_upon_a_time_in_the_west_4k_theatrical_and_restored_version_4k_uhd_bluray_us_import_ohne_dt_ton
I stay with my 2005 DVD unless the risingfree theatrical version (aka as the oneandonly) will be released
They put the scene in because they deleted the scene at the trading post; so they needed to somehow show Harmonica survived the shootout. As usual, one bad decision (deleting trading post) begets another (adding Rising). It?s all explained in this essential article http://www.fistful-of-leone.com/forums/index.php?topic=10564.msg149153#msg149153