What aspects of the "memorial banquet" for Boxer are ironic?

The next Sunday, Napoleon promises to honour Boxer with a special wreath and a memorial banquet. On the day the banquet is to be held, a large crate arrives at Animal Farm. That night, the pigs are rowdy inside the farmhouse and do not wake up until noon the next day. The animals hear a rumour that the pigs had bought a case of whisky. The Banquet had nothing to do with Boxer and only the pigs were invited. They drank whisky, a symbol of men, who the rebellion was against from the beginning.