I disagree that they would have taught it as science, yes.
Many or most of them might not have had a problem with religious instruction in taxpayer-funded schools. But instead of making that argument, the proponents of ID have tried a stealth campaign to get their vision of God in public schools. They're trying to re-write the definitions of words in an attempt to sneak faith into science classes.
And personally, I have a very hard time believing that any of the Founders would endorse that sort of dishonest tactic.
It was taught as a fact, and if someone objected the Founders would have had the objector take it up with their school board, not a court.
I'm using "creationism" as the example since it was the case at the time. "Creationism" and ID are not synonymous.
Would either of you object to teaching that life developed without a designer?