Was the sota water poisoned?

In progress...

I'm working on a post about the bitter waters given by the priest to a woman suspected of adultery (more here.) Josh has an old post in which he argues that Ibn Ezra believed the kohen added poison to the water before giving it to the woman; thus, the Sota test was a trial by ordeal, and the miracle was not that guilty women died, but that the innocent women lived.

Josh says Shadal and Avi Ezer disagree, but differently: Avi Ezer insists (a little too strongly for my liking) that Ibn Ezra is saying nothing of the sort. Shadal, on the other hand, sees what Josh sees in the Ibn Ezra but rejects the idea as "nonsense and insanity."

I agree with Josh that there is something fishy about Ibn Ezra's comment, and that something rings very false about Avi Ezer's denial; still I don't see what Shadal saw. Why is it so obvious to him (and to Josh) that the Ibn Ezra believed the kohen slipped poison into the potion?

All the relevant sources and arguments are at Josh's

Search for more information about Shadal at 4torah.com.