You raise an interesting point.
It is obvious that after January 20, an "Acting President" Pelosi could cause all manner of mischief and you give us an example.
Although it makes little difference, I think it perhaps more likely Clinton would be installed as president not via the Succession Act but rather by determination in the House.
Perhaps even more likely, and much cleaner, is that Clinton formally replaces Biden prior to the election and it is the Electors that vote him into office. Assuming, of course, the D's carry the day.
Then all early ballots for Biden would need to be discarded. Were Clinton to replace Biden in October every ballot cast for Biden could not in any way be transferred to Clinton of whoever takes Biden’s place.
Also the dangers of early voting ought to be obvious to the Dems. Had there been early voting in 2000 there likely would have been no crisis. Bush was comfortably ahead until the DWI story broke a week before the election. His lead evaporated. With early voting following the polling then he wins. This is why October Surprises are now September surprises and the debates have lost their impact.