One could argue HFCS is worse than transfat and it is used everywhere. Come on, get on a roll, FDA!
One could, if they could prove that HFCS should no longer be generally recognized as safe, as was done with trans-fats.
Your minor problem is going to be that natural foods do not contain substantial quantities of trans-fats. It's a quirk of the abiotic hydrogenation process that is used to modify naturally occurring unsaturated oils. Thus the substance is essentially artificial.
That's not the case with HFCS. The process that produces HFCS is artificial, but the very same sugars are in corn, sugarcane, fruits, berries, and various vegetables. You don't object to what the substance is -- you merely object to the form it is being provided in and how much is used.
A little thought experiment: would you have the FDA ban honey as well? It has virtually the same glucose to fructose ratio as HFCS 55 (glucose and fructose are the major sugars present at about 32 and 38% respectively), about 17% water, about 10% other sugars (especially maltose, which is a dimer of glucose), and about 3% other.
If not, then tell me the key difference between the two substances that makes one ban worthy and the other not.
Banning HFCS is simply a poor proxy for regulating that amount of sugars that are incorporated into foods. Yet we don't (currently) permit the FDA to regulate on that basis. If you want to have the argument, make the argument. Don't construct a make believe boogeyman and expect a community of nerds to buy into the myth without question.