I kinda agree with this, the whole PTSD thing felt kinda forced, like it was there just to explain why Steven's powers were going crazy, but we already know that Steven's opwers are based on his emotionional state so kinda unnecesary. Also the whole thing was dropped afterwards, like we don't see Steven trying to confront his fears by trying to get closer to the diamonds.
Also the part when everyone was crying and blaming themselves for Steven's emotional state was also kinda stupid, implying that Steven never had someone to help him with his issues, but you can't help people who don't want to be helped.