Wa Aleykum el Salam, The explanation is she may Allah be pleased with her came to ask for the inheritance from the Caliph Abu Bakr RA, He told her what you read in the narrations above, She accepted his ruling and she didn't debate him on the issue, only one Sahih narration uses the Term "Angry" but that could have been the case, Although he was extremely busy with the Murtadds and fighting Bani Hanifa and Musaylamah al Kazzab and The armies of Tulayhah and Sending the forces of Usamah as the prophet PBUH instructed then gathering the Mushaf ect... He still went to check on Fatima RA who was extremely sick at the time as he wanted her pleasure. Ali RA during his Caliphate left the land of Fadak exactly as Abu bakr RA and Umar RA did, he did not offer it to the children of Fatima RA. (Shia will use anything to make any companion a Kaffir, That's an Aqeedah).