No idea about this dude, but literally in the article you link, they reference Zenz as an independent researcher who says:
“Although it is speculative…”
Before providing his estimate and also provides other details which appear to support the story, but the article does not present as clear, hard “facts”. Also, the title isn’t some clickbait trash, and even directly says “could”.
Does it say that in the article? I don’t understand who this person is or why this discredits everything that Reuters as a news provider does.