That test isn't definitive. Most pedals are made to a sloppier class of fit than Campy, specifically so they can go into cranks that are on the small end of their tolerance range.

Chasing the crank thread, perhaps to the larger end of the tolerance range for this specific pedal (like with my Hozan tapered taps) is a valid way to keep that pedal on the road. Yes, replacing the spindle is a valid way too, but I'm too impatient to wait for the replacement to arrive, then overhaul the pedal to replace it. I'd have my tap run through it in about 2 minutes and be out riding.

Assuming that worked! I know, not necessarily a given. But we know that pedal was ridden before, ergo it had to fit a crank at one point. It hasn't grown larger since it was taken out of a crank, and the pics are so good I think we can mostly rule out damage to the thread or aluminum cold-welded into the valleys. I think it's just a tolerance mismatch.

Mark B