Every time your cat soils the tub, you most likely clean it immediately, whereas the litterbox may go an entire day before you get around to changing the litter. Given the choice of using a clean tub or dirty litterbox, your fastidious cat will naturally use the cleaner area. If you are unable to change the box more frequently, get another box so at least one of them will be clean enough for him to use. My cat prefers to use a back room closet for his litterbox. Cats like privacy to do their business.
Kitchens are usually too busy a place for cats too feel privacy.
Cats also don't like to eliminate in their dining area. Even if you don't feed your cat in your kitchen, he probably feels uncomfortable soiling in your dining area. I would take the path of least resistance and place his litterbox in the back room closet. If that is not acceptable, then I would use a covered litterbox near the closet he prefers. Spraying is a social, sexual and territorial behavior.