Tree stump in crawlspace surrounded by boards and covered in concrete?
WOW! I would be upset. It's a huge loss of space. I have never seen such a thing. Unless it's petrified, there is no reason for it. Any tree can be removed even if petrified. That is weird. Looks like cost savings to me. Hard to get a grinder in a basement. I'd talk to an engineer or architect if you don't care about the space. I