Because he fears necrothreads.
You know, old threads where sometimes are months or even years between the answers. For some cosmetic reason they find this should not be so they lock the threads.
This behaviour has no positive side but 1 big negative: If you find an answer later, you cannot help(or find help !) anymore, because a moderator locked it(i always have to think at the illogical, irrational behaviour of leftwing extremists but i don't want to say the mod is with the ANTIFA

I experienced it that often, that a old thread was found with google and it had the answer to what i searched, and the answers were sometimes YEARS after the question, BUT THEY WERE WRITTEN DOWN.
I could read them and no goodie two shoes took the chance to solve my problem away from me.
Believe me, if you look for an answer, you do not care a little bit, you do not even notice it, when the answers in a thread are years apart.
I don't know names, but all moderators should think about that and ask themselves: what good reason do i have to lock down old, revived threads. By god, which ?
Knowledge is king, not cosmetics, not the surface.