In other years the Ohio legislature has passed laws allowing a later date, but ot this year.
Personally I think it's a dirty move, but the Democrats have already shown that this year's election is dirty by arresting President Trump and unleashing the lawfare and tge FBI against him.
One more thing: If Biden gets on the ballot by signatures he will still be the one on the ballot in Ohio even if the Dummyrat convention picks someone else. Haha!