I think that the author had the conclusion wanted before picking the story that supported the desired conclusion as best. To me that story overlooks too many documented facts as well as human behavior. They complain that it requires lottery odds for the first story to happen while ignoring that one win is documented - there was a cold snap exactly when Fleming we t on vacation. Both stories require the winning odds of the mold contaminating a culture - the mold wouldn’t have needed to be identified if Fleming was deliberately experimenting with a known mold from his colleague. So the only undocumented luck left would be the use of that contaminated culture just before vacation.

And which is more likely - Fleming imagining the initial discovery happening right as he returned from vacation or that he remembered those important details but forgot more minor ones?