MDX #35 - Properties() function with TYPED flag

My publisher recently forwarded me a question from a reader about the "Using the PROPERTIES() function to retrieve data from attribute relationships" section in Chapter 1 of the book "MDX with SSAS 2012 Cookbook". "The following code seems to always return true for [Is Numeric], no matter I use the 2nd parameter 'typed' or not. Can you please explain why?"