This is in my neighbors front yard. I can see it from my front window. I keep telling him he needs to get rid of that ugly thing, and I will even remove it for him.[}] But, sigh, he just keeps ignoring me.[V] Tree is maple, about 3 to 3 1/2 feet in dia.
Try another approach ..... "Ya know that big, ugly, bulging knot on the side of your tree? Well, it's blocking my view when I back out of my driveway. We can leave the rest of the tree standing ... I'll just slice that one piece off as a favor." []
Since your neighbor knows you are a woodworker and, thus, a "tree expert", just tell him it really isn't healthy for the tree and to ensure a long life for the tree it really should be removed. Hey, it might work.[]
I was thinking along the same lines as Brad (Ptolemy) tell your neighbor that its some sort of tree cancer, if you don't remove it the whole tree could die and you would be more than happy to remove it for free.
He (the neighbor) just smiles and says he likes the tree just the way it is. And he his watching me.[!] Closely. That burl wraps around almost to where you can see it in the picture, and is about 3 feet from top to bottom.