Why does my Sim do his cooking prep in the bathroom?

That's a very nice looking kitchen. And huge. I don't usually place counters in my bathrooms, I prefer the standalone sinks, so I rarely encounter such heresy in my game. Also, I think sometimes it's an issue of first placed, first used object, that causes the sim to learn and use a certain path for his tasks. So just place and use kitchen counters first, and only afterwards add them elsewhere.