Iirc, Frisk can only use the file if they're dead. Although it's a bit weird, since Omega Flowey could spam it in the midst of a fight. Although, from what Flowey says on the Genocide Route, using time manipulation is basically thought based, since his base state, before he even knew about the power, could rewind time after he was erased from existence, just because of the will to do so. I think it's not unlikely that Frisk could undo the sealing in a similar manner. Although, since it's a higher dimensional construct, would it's sealing effect be undone by time manipulation?