Trump may soon pardon him?
I think Trump should at least commute the sentence. However, whilst the gears of justice often move slowly as they grind an innocent person down, it is often best for the nation, that the gears are turned until justice is actually achieved.
A good option for the President might be to threaten a pardon or commutation unless the current trial is voided and a new one, with a different judge and jury, is started. If prosecutors are comfortable with their case, they should welcome a chance to publicly persecute Stone for another year.
If there is objection to a fair trial, then the case is dropped and justice is restored.