Hm. Unfortunate that there was no achievement testing. I assume that means that the school's other measures (grades, progress monitoring data, etc.) found him to be meeting or exceeding expectations for his grade level. Still, that wouldn't have captured excessive effort or time needed to perform at that level, which is in the category of considerations for a 504 accommodation plan. Glad to hear that he has found a more adaptive way to manifest his frustration, but I'd prefer supports that allow him to reduce that frustration. Organization clearly is an issue, which is certainly an ADHD trait.
Do ask again, if you have more questions.
