Rap Rap Rap Rap Rapping

According to The Sun (an often inaccurate source despite being the biggest selling daily publication in the UK) Tim Burton has given Sacha Baron Cohen permission to not sing his role as Pirelli in Sweeney Todd but instead rap it. They quote an insider as saying "Any professional singer would struggle so Sacha has been told to go for a rap style. It will be a bit like Jim Broadbent's performance in Moulin Rouge. That won him a BAFTA. Sacha is going to do a fantastic job but he couldn't cut it with the singing. His voice was too low."

Maybe somebody else should have been cast in the role, then?