You can replace "excuses" with "justifications" and "non-adopters" with "adopters" and get a similar argument in the other direction.

This amounts to Bulverism: if you assume that your opponents are wrong (i.e. you assume that their excuses got successfully knocked down), then you can claim there must be some irrationality that explains why they remain your opponents. But you're not supposed to assume that. It's like saying "excuses for opposing homeopathy get knocked down, but the allopaths don't become homeopaths. Obviously this shows they are alloapths for irrational reasons with nothing to do with the science".