Just use your brain. Nintendo has roughly 8600 employees, 3000 in Japan alone. Salaries are the vast majority of indirect operating costs in any company. If Iwata halving his salary pays to avoid layoffs, then his salary had to be a huge percentage of Nintendo's operating costs and the WiiU failure would've been the least of their problems.

Nintendo regularly reports operating costs in the order of several billions of dollars quarter over quarter, a majority of them would be salaries or manufacturing. Even if Iwata was paid a single billion dollars a year, and halved that, it would barely amount to a rounding error on the accounting. It was just a PR movement, and most Japanese salary men recognize it as such. It is something done for media clout because "we will just pay you with the piggy bank money" doesn't add any drama worth a headline.

And Nintendo working conditions have always been controversial. While they are by far not the worst of Japanese corporate employers. They are not exactly saints either, falling into the same patterns that plague the Japanese office culture. Specially the abuse of employees qualified as independent contractors and unpaid overwork. It triggered a labor complaint in the US in 2022. They have become a bit better very recently, apparently. But it is still one of the oldest and most traditional fucking companies in the planet, they carry some troubling organizational culture sometimes. But this is hard to prove because secrecy and not advocating for oneself is part of said culture.