Bossy father in law

by Racheal

At my son's third birthday party, which we had at my in laws house, my father in law decided he was going to start bossing my 3 yr old around. My son asked to be excused from the table and my husband and I both said yes. Right then my father in law pointed his finger at my son and said "no you sit right there and eat your hot dog right now". I gracefully removed my son to the other room without a word. When my son wanted to open one of his gifts to play with I told him yes. My father in law says "no you cannot open that right now" I gracefully removed my son from the room.
This went on all night. I did not say anything for two reasons. One I did not know what to say and two it was my son's birthday and I knew if I did say something my father in law would blow up. He has a very short fuse.
How can I gracefully tell him to stop bossing my son around and is it wise to address that it happened at the birthday party a month ago, or wait until it happens again?