Did Ali ibn Abi Talib send the Messenger's ring to affirm Abu Bakr's pledge of allegiance at Saqifah because he was preoccupied with preparing the Prophet [for burial]?

The authenticity of this report has not been established. What has been established is that Ali (may Allah be pleased with him) personally pledged allegiance to Abu Bakr in the Prophet's Mosque while Abu Bakr was on the minbar.