I agree. Hardly a chapter goes by without somebody being a dick to somebody else for no good reason. For a country that prides politeness as much as the Japanese do, it's kind of wacky.
His whole strategy was to hide the fact that he'd made a pact with his wife not to eat delicious food until she got better. Rather than just telling the others that, he decided to act like an asshole to people who are, ostensibly his friends or associates. When my gf and I watched this episode of the anime together, she went on at length about how ridiculous Inamori's stance was.