Which, of course, is flawed logic for many possible reasons. The author of The Girl With the Dragon Tattoo only wrote 3 books before he suddenly died. This dial maker easily could have just begun doing work before he met his demise, or just got tired of it, or ran out of money, or something happened in his life forcing him to quit. Sh#t happens all the time to people.
Mayer is probably right, but his theory could be picked apart and there is no way to prove either way.