I’m just guessing but I suspect that the artist felt that it dominated the painting. Personally I like it better without the pig.
You're going to have to do some clicking [I don't know how else to do it; it's too large for a screen capture], but your interesting comment is addressed.
Click - case studies
Click - 2009 Historical Rewards: A Dutch and a Flemish Discovery.
Click - Enter
The first four pages contain interesting historical and genre info.