Interesting discussion. But here's another angle to view it from. How many would brew a beer recipe that called for iodine? Not me. It was an oopsy and I wouldn't drink it. I wonder how many people that say they would drink it, would also say that they would not drink a BMC if their life depended on it. Seems counterintuitive. Im in the dump it and learn the lesson camp.
But Jim, there are a lot of things we put into beer that I would not want to consume straight. Does your beer call for lactic acid or gelatin or calcium chloride?
Fortunately my life does not depend on what beer I am going to drink, but it makes sense to me to taste a sample before tossing the batch.
I'd be more worried about a half a gallon of nasty blow off water than I would the iodine. Who knows what lands in a blow off bucket?
I'd still probably taste it before dumping it.
Iodophor does not stay dissolved in solution for a very long time, maybe 24-48 hours, if not in a sealed container. If the blow off bucket was exposed to to the atmosphere, it's likely that the vast majority of the Iodophor has returned to the atmosphere. Was the blow off solution clear, or still an amber color? If it was clear, there's little to no Iodophor left. It may be hard to tell if there's a lot of yeast in the blow off bucket.
Adding this amount of solution back to the beer will cause more problems with flavor dilution and scum from the blow off than human toxicity from residual Iodophor, IMO.