Quick note, he needs to figure this out, but besides that he should ask DA if the plea would leave ajudification withheld for either.
If ajudification is withhold he's not considered "convicted of a felony" and it can years later be exponged, unless of course he violates probation or rehab order, then he's considered ajudicated guilty (a/k/a ajudged guilty a/k/a convicted of a felony)