The reading probe data you've reported tends to make me think less of dyslexia, as the reading behavior he displayed during the probes was much better than grade appropriate, and certainly within the range for an MG student. It also was different from what you observe day to day, and suggests that the difference is attention and motivation--which is much more ADHD than dyslexia (although highly-motivated compensated dyslexics can also "turn it on" for brief periods of time).
And more importantly, the reading probe data establishes that his ability to decode above-grade-level text is high, so whether his typical errors and dysfluent reading are because of vulnerabilities in sustained attention/impulse control, or because of automaticity deficits, the likelihood of significant ROI on a classical OG reading intervention is low. A different type of intervention would be indicated (e.g., a fluency intervention, if, for example, he's reading fluently only in bursts, and only with great effort). The behaviors you are describing sound more like self-monitoring weaknesses to me (i.e., impulsivity and inattention combined).
His reading approach also doesn't appear to be affecting his overall comprehension much. (Can't go by the stagnating MAP scores, as he's probably running into ceiling effects on the test, and the very large error bars up in those high percentiles.) If they haven't yet, the school should probably consider switching him over to the MAP 6+ for reading, since his fall reading probe appears to have put him at a beginning sixth grade level or better.
