I was doing some research on this.
In the data they're right next to the sprites for winning a bonus game
I found this doing research on this. A very old forum thread on it.
viewtopic.php?t=1383In which, a new theory showed up. The mourning animation was played upon startup of the game. Maybe only for the first time, though? Additionally, I believe that Rareware had something planned for Stronghold Showdown. Perhaps, the K.rool Boss fight there instead of the flying krock which is totally a reference to the gargantuan. I still don’t believe it was originally planned to be empty. But at the same time it was a bluff ending/boss fight. Perhaps it was akin to DKC1 fake credits and fake ending. It sure reminds me of that fact.