
Note in the lower right corner the mounting strategy. This means you can't drop the table any lower than that - ie: no short horizontal boring.
Also of note, in the photo they changed how the table was mounted. It appears they switched from using all 4 posts on the extension table to just using two. Clearly this could make you subject to out-of-square issues. Then again, this may be just a weird camera angle.

That photo shows the table with all four posts in use...perhaps flipping it around would solve the issue they were seeing that drove the use of only two mounting posts.
If you look carefully in the lower left you see the bolt heads going through the allen wrench holes.