Chemicals physical properties can be completely different depending on physical state...
The FDA has their GRAS list but they don't "approve" any chemical. Generally, you can put whatever you want in food as long as it does not harm the consumer. That's the FDA standard, do no harm.
21 CFR 172.151 speaks of 2,3 pentanedione being used as a flavorant ... but it still must pass the do not harm standard too.
Major components of vaping solutions include propylene glycol and glycerin. Both are usually OK as a food additive. But vaping is totally different.
Since most people who vape also smoke I hate to think what sucking into the lungs organic solvents do to the material in the lung that normally would not be exposed to such solvents.
So I advise against vaping. But its their body, they can do what they want.
Good information to know for the public. A little personal responsibility of checking out materials you want to put into your body and their effects is what's called for, not government regulation.
In October, the Journal Sentinel exposed two cases of acute lung injuries that doctors said were tied to vaping. The news organization's investigation has also revealed that diacetyl and 2,3-pentanedione are now risking the health of coffee workers across the country. OP linked story
Well, there you have it, all the proof we need, right? We'll see about this lawsuit...