I know nothing about this issue...

However, as hard as it may be and perhaps it's a stretch, there may be mitigating circumstances surrounding remedial "treatment".
It may help in the court's view that your son volunteers for a substance abuse program and a plea deal can be negotiated by the attorney in the case of a positive outcome.

Just a suggestion and I hate to see dreams shattered for something we all are aware of can happen and could have happened to any of us at some time.

Things aren't the way they used to be and I have seen several examples of convicted DUI offenders with successful airline careers but that was days gone by...

Best of luck with your son, he must feel terrible and I wish him all the best in this case.