On one hand I am surprised that Kerotan calls out Sony fans, but on the other hand it actually makes a lot of sense. If Japan is brushed off as irrelevant due to its low PS4 sales, then Kerotan's narrative of excellent PS4 sales in Japan has no chance of working at all. He can't have members of his own team undermine him so much.
The rumor is that Sony paid to get Monster Hunter World (Monster Hunter 5 according to Capcom) on the PS4 and have Switch left out at the same time. If this can be confirmed to be true in the near future, then it will be irrefutable that Sony still cares about Japan.
Beyond that, Japan is obviously home to many prestigious third party publishers, so it's important to maintain a good presence in the country. Sony understands as much.