He blew a .00 but there could've been drugs involved. It'll depend on what the statute says and how it is written. In SC, he'd be probably dropped to either a reckless or inattentive driving. Or a trial, but, I don't think it's that bad. Those SFS tests aren't all they're cracked up to be.
Go reread the statute. In SC and Florida (where this occurred) and pretty much every jurisdiction (didn't check all 51, but didn't find any exception in any I did check) driving under the influence of a controlled opioid even if legally prescribed is a DUI.