The BBT-59 is definitely a correct choice in tool to use. However, you shouldn't ever break free tight things with a torque wrench. Ideally you would never use a torque wrench in the loosening direction. It's a bad practice. If you know the thing you're loosening is within the torque range of the wrench and its current setting you can kind of cheat there if you really want to, but loosening arbitrarily tight things like a BB cup is not a job for a torque wrench. Use a breaker bar.
The new Park external BB tools (BBT-59 and BBT-49) have inexplicably broken from the tradition of such tools having large external wrench flats for a big adjustable wrench, such as their and everyone elses' first generation socket-type external BB tools. Having external wrench flats allows you to play the trick of using a QR skewer or bolt plus some big washers to clamp the tool to the cup so it can't slip in case you're dealing with a tight or stuck cup. So instead you just have to position everything so you're using your body to keep the tool pushing hard inward as you turn it. If there's any thought process here at all, they probably did it this way because they made them out of aluminum so they can be non-marring, but didn't want people trying to turn the outside at high force with adjustable wrenches, so they eliminated the option. But if they cared about that they could have found a way to create a non marring contact surface and a steel body, same as using the freebie plastic adapter tool that Shimano includes with these BBs if bought aftermarket.
As for how to get it off, as in the comments make sure you're turning the right way (ISO BB shells have reverse threaded right cups). Usually the technique for a difficult one of these with that tool would be bike on the ground, knee or shin pressing the wrench inward against the bike to prevent slipping, tool started at around 45-60ish degree angle across front triangle, and try to find a way of putting all your body weight into it, or even use your foot. Having someone hold down the back wheel can help.