Health authorities in Europe are known for being more stringent than the FDA, so that doesn't quite track. Also, the FDA doesn't regulate alcohol in the US. If synthehol is sold and legally recognized as a foodstuff, the manufacturer would only need to show that it's less toxic than Cheetos or Mountain Dew. Or in other words - it's manufactured in clean conditions and has a negligible LD50.
The FDA might regulate a substitute if it were marketed as a treatment for alcoholism... as a medication for a discrete indication. But it's more likely to fall to a regulator like the DEA (or ATF if they want to get really funky). It could result in a strange intersection of regulatory authority - much like the current thing with legalized medicinal and recreational pot.
And honestly - both instances (pot and synthehol) would come down to a fight over who gets the money we spend on getting fucked up on a Friday night. The alcohol industry has got a near monopoly on that at the moment. That's why a lot of the pushback against recreational legalization of pot seems to be coming from the alcohol industry.
A direct alcohol substitute seems like it would be even more in the crosshairs. Prohibition is the obvious option for the current monopoly industry to push for. If lawmakers leave an opening for medicinal use, the next obvious solution is labeling it as a Schedule II drug where the only legal use would be as a treatment for alcoholism (compare: amphetamines for ADHD or morphine for pain). There's probably enough profit in that indication that hundreds of thousands of dollars to pay for trials would be a pittance for any company that wanted to pursue it as a drug. And the alcohol industry would view that as an acceptable loss of customers who were already out the door.