That's not how he presented it, he presented it that they have the info to identify each cheater. He said (I am paraphrasing), "The net is tightening and we will catch you". He dared them to try to get away with it. He was shaking them down. My point is, I would call him on it, if they do have the data then they can prove my (hypothetical me) innocence.
If they don't then he is shaking people down, which is not entirely fair. If they don't have the data then the innocent don't deserve to be shook down for a witch hunt. He should just tell the class, we know some of you cheated, we don't have the data to unwind who did and who did not, so it's a do over for all of you. To the ones that did not, I am sorry but you can thank your fellow classmate.
I would be pissed if they came clean and said they can't sort it out, but I would not blame the professor for the actions of others. As it sits, with the claims that they know who the cheater are, I would hold it against the administration for holding me as a non-cheater to account when they claim to have proof that exonerates me.