A third of the angels rebelled against God, as it is written: Revelation 12:4 - And his tail drew the third part of the stars of heaven, and did cast them to the earth: and the dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born.
Also:Revelation 12:12 - Therefore rejoice, ye heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea! for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time.
He{Satan}deceived a third of the angels, so why would God use Gabriel to send the message to muhammed. The Bible clearly states that Jesus{The Word}direct words from God verbatim was the clearsest way to relay His message to the LOST.