But why would he burn it if he went to all the trouble to build them up?
The true question is: Why wouldn't he?
I build entire homes with the sole purpose of blowing them up later in time, I mean really work on these homes, just because it's fun. When you make something large and have no idea what to do with it, then you should always consider the option of TNT and/or fire.
But who cares, as long as he has fun with his trees! Dang trees...