This is correct behavior. foo.method is syntactic sugar for [foo method]—a straight conversion with identical semantics. Similarly foo.prop = bar is syntactic sugar for [foo setProp:bar], again with identical semantics. This transformation is implemented in the compiler. Thus you can use dot notation to call 0-parameter methods as in foo.doSomething instead of [foo doSomething]. Of course, if you do this, you are evil.
The fact that the callee is a class instance doesn’t mater because in Objective-C, classes are also objects. Using dot notation on a class calls the parameterless method on that class.
Dot notation is described in the Objective-C Programming Language document.