Context: this guy has a very wide infrasternal angle, he’s older, and this angle doesn’t change a whole lot with training. Will he have trouble with squatting just because of this shape?
More context: see the initial prompt for this question about heels-elevated squatting.
People with wide infrasternal angles are just “wide” people. They need to be able to expand the thorax anterior-to-posterior. He might have normal hip rotation in a table test, but with his width, standing up could drive the weight forward and then steal the motion away. These people would show limitations in their squat.
The prescription is the same as for progressing someone who seems to need heel elevation to squat: load them anteriorly first and teach them how to keep their weight backwards.
You might try a plate squat, goblet squat, or two kettlebell front squat to teach this.