All it takes is a few thousandths of an inch of the valve being held open to keep the engine from starting. The valves will not hit the piston and the engine won't start.
Here is a quote from the Ethanol Producers Magazine relating to this issue:
Intake Valve Sticking
Intake valve sticking is a possible, unintended consequence of using poorly formulated gasoline additives in gasoline. This occurs when some of the additive builds up in the annular space between the intake valve stem and the valve guide in the cylinder head. At low temperatures, any build-up in this area becomes more viscous and inhibits valve movement. Under extreme conditions, the valve spring cannot close the intake valve, resulting in a loss of compression. Consequently, the engine doesn't start.
Modern gasoline additives are formulated to prevent this problem in normal gasoline. However, recent research has shown that ethanol can make intake valve sticking even more severe and confirms the need to test gasoline additives in the full range of fuels in which they will be used, including the low-level ethanol blends widely available in the U.S. market. More importantly, in the more extreme case of E85, it points out the need for specific additives for E85 that are designed to treat the problems without causing unwanted side effects, such as intake valve sticking.