Mirandizing of Speedbump's baby brother

I was thinking today about the Mirandizing of Speedbump's baby brother.

The point of all that has to do with fair trials and all, right?

So, if you take him out and beat him with a hose until he's confessing every sin he ever committed, every name he ever knew, and cusswords he didn't even know he remembered, you can't use those statements against him in court. So?

Since he's pretty much guaranteed to be a jailbird for life anyway, if not electric grill fodder?