In A Lesson Before Dying, why does Grant refuse to sit down or take any supper while he is waiting for Henry Pichot?

In A Lesson Before Dying, Grant
refuses to take dinner at Mr. Henri's house because he does not respect Mr. Henri.  To
appease Miss Emma and his aunt, Grant has already used the back door to enter the home,
something his aunt Lou told him never to do again.  Grant has gone to university and is
educated, but whites around him such as Mr. Henri, refuse to see him as a peer.  Even
though slavery is over, racial tension still divides people in the area.  If Grant were
to eat at Mr. Henri's house, he would not do so in the company of Mr. Henri--he would
have to eat back in the kitchen with the maid Inez.  Taking the food would symbolize
Grant's acceptance of being treated like a lower person, so he refuses to eat at Mr.
Henri's house.  Grant's actions show the reader that Grant is proud of who he is and
will not stand for being treated poorly.