وكذبه أي كذب الخبر عدمها
Its falsehood is the absence of that agreement.
On this account truth and falsehood divide assertoric reports by whether their content corresponds to reality. Sincere belief does not make an untrue assertion true.
If Zayd is absent and someone asserts that he is present, the reported state does not obtain. Hence the report is false under the majority criterion, even if its speaker is sincerely mistaken. The truth value of a report should not be collapsed into a moral judgment about deliberate deception.