Very easily. They want a conviction. Doesn’t matter if it will be overturned on appeal, because that won’t happen until after the election.
There are two ways in which that might not be true. Nominally, normal course of events, reversal would not occur fast. But that is an extreme case of “justice delayed is justice denied” - so extreme that Trump could appeal all the way to SCOTUS, IMHO, on the basis that no lower court would take the appeal on a timely basis.It would be like allowing an execution to occur while the defendant is waiting for his appeal to be heard. Waging lawfare against the nominee of a major political party is no small thing.