I know many things are just personal preferences. However, as expert writing reviews for more than one decade, it is hard to believe he is a hater of a specific brand.
Actually, Rockwell clearly has become a hater of Nikon. His write-up of the Z9 development announcement (which he calls a "review", a total lie) is a blatantly biased screed.
Bias is actually pretty easy to detect; it reveals itself clearly when people describe equal events in different ways, or criticize something when one party does it, then ignore the same action when another party does it.
Nikon made the Z9 development announcement on March 10 and Rockwell published his screed about it on March 13, three days later.
On April 14, Canon, the brand Rockwell now reveres, did exactly the same thing as Nikon had done; they made a development announcement of the EOS R3. Everything Rockwell said about the Z9 announcement he could have said about Canon's R3 announcement. The two events were nearly identical.
Instead, Rockwell lauded the one detail Canon provided about the R3 and ended his write-up with "Bravo!" No scathing and sarcastic comments about the lack of detail provided by Canon; no commentary about how the camera is useless, or a "unicorn", because it's not available yet, yada, yada, yada. (Scroll down on this page to see it:
https://www.kenrockwell.com/tech/00-new-today.htm)
Compare that to the way DPReview treated both announcements. DPReview treated both events very similarly, as, of course, they should have, since the events are almost identical.
Rockwell has always been a cesspool of subjective opinions, many of them stupid. But with Nikon he's fallen into a pattern I've seen many times before in people who switch brand loyalties (or loyalties of any kind, really); he's become a blatant hater of his former love. He feels they let him down, which he feels makes him look silly for championing them, and now he's out for revenge.