I ended up being able to get the nuts off without too much headache using an electric impact gun. The troublesome clamp I disassembled and cleaned out with sandpaper. Overall the inside of the flex pipe looked fine, the outside just had a flat section about 2-3in back which makes the braid look bulged.
As a cheap as free option I took the whole joint apart, used 120 grit sandpaper to get the crud off of all the mating and clamping surfaces AND most importantly made sure I shoved the tailpipe side firmly into the head pipe section while tightening the clamp bolt down.
Results on a cold start and 30min of test driving and idling messing with trans fluid and other things was no more exhaust leak sounds nor rattle. Tomorrow I’ll take it on an hour long drive to try to get the trans temp up and listen for the rattle that came in at ~35mph under light throttle but only after everything was at temp.