If the condition is real, it could be possible that she can stink of booze yet be 100% straight due to tolerance.
Possibly at lower BAC's, but there's no way she's walking around at 0.30 and not impaired. Tolerance generally means you can clear out the ethanol faster from your system, but if her levels are that high she would definitely be feeling it. A hallmark of gut-fermentation syndrome is that those suffering from it feel intoxicated after consuming carbohydrates. One study showed that 1 gram of dextrose led to a BAC of roughly 0.0025 in these patients. If this can be extrapolated linearly (and there's no data to support that, just a WAG on my part), then it would take over a kilo of carbs to get in the ballpark she was reported at. Something just doesn't add up for me here. Then again, I'm not an expert and I'm just going by what I'm seeing in the article (reported by a journalist who is likely not an expert, either).
More conclusive evidence would be a positive stool culture for S. cerevesiae, but I didn't see any mention of that in the article.
I would hope they are putting as much effort into to how to kill the yeast causing the issue as they are putting into to defending the DUI. I'm not a doctor, biologist or chemist but one would think you need to identify the strain of yeast and attempt to selectively remove it from her gut to really solve the problem.
It's not my place to judge if she is impaired while driving at this point so I'm leaving that question alone.
Just hoping she is being treated in addition to being judged.
Treatment is typically two courses of antifungals, along with probiotics to ensure proper recolonization of the gut. The article does mention that she is being treated. But if this is BS, it would be a good way to explain a negative stool culture at this point if that ever became an issue in her case.