Right, so since he -- may Allah bless him and grant him peace! -- did not strive against them, then they were believers, and not disbelievers or hypocrites.
We also know that the Prophet -- may Allah bless him and grant him peace! -- would trust and believe in those who were believers, as we are told in 9:61
And among them are those who abuse the Prophet and say, "He is an ear." Say, "[It is] an ear of goodness for you that believes in Allah and believes the believers and [is] a mercy to those who believe among you." And those who abuse the Messenger of Allah - for them is a painful punishment. (Sahih International translation, emphasis added).
So those who baselessly accuse Abu Bakr, may Allah be pleased with him, of lieing in the matter of Fadak are actually going against the Sunna, are they not? Unless, of course, he was a hypocrite -- but wait a minute, in that case, why didn't the Messenger -- may Allah bless him and grant him peace! -- strive hard against him and act harshly with him?
Come on, all you Imami Shias -- I want to hear your response to this! Seriously, it seems to me that the Book of Allah is very generously endowed with all kinds of unexpected evidence against your religion, including evidence that the Sunnis have not even considered yet.