Given the translation I think it would actually evaluate to true :) I guess I just don't see enough value in special casing constants, but if you want to see a precedent of doing this look at the exception we throw when passing a null IEnumerable<T> to Enumerable.Contains. This is the only case I can remember.
An unhandled exception of type 'System.NotSupportedException' occurred in mscorlib.dll
Additional information: Unable to create a null constant value of type 'System.Collections.Generic.List`1[[System.Guid, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]'. Only entity types, enumeration types or primitive types are supported in this context.