Great article, thanks for sharing.
Maybe it's just a typo, but when he says, "Patrick Cleburne formed sharpshooter battalions in multiple Georgia, Alabama, Tennessee, Mississippi, and Louisiana battalions in the Army of Tennessee on the divisional level. They used Whitworth and Kerr rifles and many P1853 and P1860 Enfield rifles and stressed range estimation and marksmanship training." I don't think Cleburne was responsible for the S.S. battalions in the army, at least not those outside of his division. My understanding is that Cleburne formed a small contingent of sharpshooters within his division, armed with Whitworth or Kerr rifles, though he also had all the troops in his division trained in accordance to Hythe's manual to some degree. I've read that there was a similar contingent in Cheatham's Division as well, maybe based on Cleburne's.
There was the 15th Mississippi Sharpshooter Battalion in Wood's Brigade of Cleburne's Division, but I don't know if Cleburne himself had any part in its organization. Others in the AoT, like the 14th Louisiana Sharpshooter Battalion, were organized from disbanded units, without any special attention given to hand-picked men or marksmanship.
He does later say, "General Patrick Cleburne developed sniper detachments in April 1863 using Whitworths. Shooting matches determined the recipients, and training in drill, rifle maintenance, and range estimation were stressed. His marksmen got 30 Whitworths and 16 Kerr rifles at Dalton, Georgia, before the North Georgia campaign."