Every manner of person has his or her code that defines proper and improper behavior. For Boston “hit men” killing for money is just good business. For stylish people wearing a striped shirt with plaid trousers is very sinful.
When the Pharisee in today’s Gospel asked, “Why does your master eat with sinners?” he was putting his moral code on view. That code of his saw pork and shell fish as unclean things; and it not only saw anyone consuming such things to be unclean, it saw anyone mixing with such people as unclean. In his eyes Jesus was making himself unclean by his dining with unclean people.
The code Jesus lived by didn’t turn away from such uncleanness. What it turned from other than sinfulness was unkind behavior. He had urged Matthew to leave tax collecting to follow him; but he paid the other tax collectors the compliment of dining with them. He knew that tax collecting was needed to maintain orderly lives for millions of citizens, and he knew the tax collectors there were doing their best to support their families.
What offended him was the way the Pharisees scorned people, hurting their feelings.