This cab appears in great condition...
Ya think that might be why he wants it? He's making a dedicated driving cabinet, so modifications should be minimal if any.
If he really wants one, a dead and decrepit one may surface.
Hey, we want you to wait for a POS cabinet that will cost you a lot of your time and more money to restore, if one shows up at all. At least this one will still be safe in her garage with the battery eating away at the board.

As previously stated, who knows if it still works. If it does, great! Pull the boards, cut off the battery and sell it to one of many people who are ripping their hair out either trying to repair an acid damaged board, or looking for a working one for their dedicated machines. The longer it stays in her garage, the more probability that it's not going to be working.
If you buy it and it works, if it makes you feel better, try and sell it. You have more contacts and know where to list this in your local area for maximum exposure. If nobody is interested, then you know it would still be sitting in her garage rotting away.