I agree that Cato's interests indeed changed him. From any accounts I've read, the Marcus Porcius who inherited his father's Sabine farm treated his slaves very well, sharing the produce and profits with them but by the time he died he was considered extremely inhumane to his slaves.

I've seen him described as a "remorseless self-propagandist" and for a guy who didn't care who he stepped on to get ahead, including possibly Rome's greatest general, this seems to be extremely accurate