Why do the people of Umuofia want the District Commissioner's men to bury Okonkwo?

Okonkwo has committed an offense against the earth by hanging himself, and thus cannot be touched by the villagers.
It is an abomination against the Earth for a man to take his own life, and so his body becomes evil. It is against Umuofian customs to touch a man who commited suicide, and so only strangers can bury Okonkwo.