As you point out, some sources credit the concentration to Trudeau. But he wasn't even a Confederate officer--his rank was in the LA militia--and thus had no direct authority to order anybody about. At Shiloh he was a volunteer adc to Beauregard (an old friend from LA) and would only have had ordering authority derived from Beauregard.
It would seem that Ruggles, Shoup or Bankhead would be the more likely ones to deserve credit for this.