...and his counter argument is going to be based on due process and arguing that because he wasn't openly engaged in insurrection that any accusation that he should be disqualified should have to be proven by due process of law.

The sad thing is, that's a totally reasonable take. Which is why his legal team is also going to delay as hard as possible, until they can argue that still having the trial prior to the election is tantamount to election interference and it should be postponed until afterwards.

Because the only chance he has of getting away with any of it is getting elected or getting a GOP president who will pardon him.