Yes, under the current situation the xtra seat would have been blocked. The FA sat in the seat all but a half-hour of a limited-service 2+ hour flight. I did ask. She said I should have been informed that FA would use it. But this upgrade was sold as a guaranteed solo seat: It stated that when sold online at delta.com. Maybe people who fly a lot more than I do now know that a FA might take a seat in this arrangement, but I did not. I would have never paid extra for the upgrade to Comfort + plus empty 2x2 seat had I known that. There were plenty of empty C+ seats ahead of us so I am not sure why she chose this one. So I am posting this for people who might get sold this bogus upgrade in the next month or two.

Public transit is definitely a potential vector for Covid.