A rather huge error indeed, and a long-lived one! (When did TF-5 come out? And this is just now being noticed?) The whole reason I started using TF-5 is because it was clearly stated that it was alkaline.
Even so, the reduction in acidity (or whatever other differences) it may have over my Ilford Hypam and Kodak Flexicolor Fixer has eliminated any pinhole problems I've had with Efke films. But I suppose that I should switch to TF-4 for my PMK negs.