It was to give him an "out" to resolve the issue in a way that's positive to both of them. He didn't have to write a PR blog post. He just had to state the facts:

His account was linked to one involved in fraudulent activity.

He's working with Apple to get his account unlinked from the fraudulent one.

That's it! He doesn't have to admit wrongdoing and Apple (despite being very confident they didn't make a mistake) gives him the benefit of the doubt and unlinks the account. Instead, he decided to dig his own App Store grave.

Because he wrote the blog post that started this whole thing and accused Apple of doing the wrong thing. Apple just wanted him to essentially post a correction.