The guy who wrote it, Eric Bogle, isn't that impressed with the cover version either, as it's missed out big chunks of the lyrics as the words don't fit the sentiment of the occasion. More than half of the verses of the original have been cut as it's a fairly strong anti-war song, and talks about 'all the killing and dying being in vain'. Not really what the RBL appeal is about.
It's not been banned, it just didn't make it onto the R1/R2 playlists because it isn't very good. DJs can still play it if they choose to.
Just to make the blood run properly cold, they're re-working 'Feed the World' for this Christmas because it's the 30th anniversary... it'll be terrible.