When I followed out the FAG cite, it linked to a biography on another site which says the following:
At dawn, 11 Nov 1583, the Moriartys with Daniel O'Kelly, one of the soldiers, took the lead of the band up the glen, and rushed with a loud shout to the cabin where the Earl's party had lain. All escaped except a venerable looking man, a woman, and a boy. O'Kelly, who entered first, aimed a blow with his sword and almost severed the arm of the old man, who cried: "I am the Earl of Desmond: spare my life". O'Kelly immediately cut off his head, which was forwarded to London and impaled on the bridge. His body, after being concealed for some time by the peasantry, was ultimately interred in the little chapel of Kilnamanagh, near Castleisland. The spot where the Earl was killed is still pointed out as Bothar-an-Iarla, and the trunk of an old tree under which his body was thrown, remained in 1850.
This bio does not cite sources for each fact. At the bottom of the bio, it generally cites the following sources:
Burke, Sir Bernard. Dormant, Abeyant, Forfeited, and Extinct Peerages. London, 1866
Calendar of the Carew Manusripts. 4 vols. London, 1869-73
Cox, Richard. History of Ireland. London, 1689
Haverty, Martin. History of Ireland. Dublin 1860.
Webb, Alfred. A Compendium of Irish Biography (Dublin: M.H. Gill & Son, 1878) pp. 140-144.
I'm fairly sure this is the basis on which the category was created.
The current St Kilian's was built in 1978 after the ancient Church of St Kevin and the castle at Kilnamanagh were destroyed in 1974 as part of the building of a large housing development.
But none of that changes the point that it could just as well be covered in the biography section and there is no reason for a made up cemetery category as there is no possibility of grouping this profile with others buried at the same site.