Because the house was a repo. This happens a lot around Ft. Hood and any other large military base. Young guys get over their head, or buy a house when married, then get divorced, orders, or separate from service and can no longer afford the house or don't care enough to keep paying for it because they don't understand the ramifications.
I understand that the house was a repo, but why would someone leave a multi-thousand dollar bike laying around? Even if it wasn't mobile because of the clutch, I would make all the effort I could to get that bike out of there. It must not have been that important to the guy.