"The impossibly encyclopedic website for American folk songs, Mudcat.org, has zero entries for 'Hicarmichael' – not even any forum posts (of which there are usually about a hundred for any song) have dared to mention it."
http://nodepression.com/article/unsettling-world-dillard-chandler

I dare! The reason the song is taboo is because of a racist element to it. The sheriff was white and the man who killed him was black, described in the song as "the nigger [who] shot him dead."
I only came across this due to my interest in another song in the Dillard Chandler repertoire. According to Devon Leger, "Though this song has been wiped from all folk databases, there are some strange and powerful lines in the verses. Like:

I’ll tell you boys it will not do a wrecked life to live
It will not do to take a life of any one for their life you can not give."