There is nothing wrong with disbelieving what you have comprehensively evaluated and deemed to be impossible. After all, can not be true is the definition of impossible.
Argument from incredulity deals with whether the process of evaluation itself is flawed, not whether you should accept the logical consequence of the outcome of the evaluation in the absence of new evidence.
Argument from incredulity deals with whether the process of evaluation itself is flawed, not whether you should accept the logical consequence of the outcome of the evaluation in the absence of new evidence.