When someone comes along and proclaims 2+2=5, just because someone is right that they're incorrect doesn't mean their own assertion that 2+2=3 is any more correct, or that their reasoning for believing the original person was wrong has any validity.
Being accidentally correct is only barely better than being wrong, and for many uses (such as when the reasoning is extrapolated and used elsewhere) is no better at all.
They're not claiming 2+2=3, they're showing that the same methodology that proclaimed 2+2=5 also proclaims (as best as they can determine give the flawed documentation of the methodology) that 3+3=7, 1+1=3 and 17+17=137