It may be hard for him to re-establish trust. Maintaining xz for more than a decade then doing this would be quite a "long con" but if HN threads are any indication, many will still be suspicious.
His commits on these links look legit to me. It's a sad situation for him if he wasn't involved.
Honestly, he should call it quits and just drop xz utils and move on with life.
He maintained it for 15 years and struggled to get anyone else to help until Jia showed up. Meanwhile the Linux ecosystem depended on it.
The Linux ecosystem will either figure shit out and maintain it or move into a different archive library.
His commits on these links look legit to me. It's a sad situation for him if he wasn't involved.