I noticed that function leads through all of the platform specific string functions which is all sorts of wrapped up in macros, which are difficult to track down the actual conditions and code that is returning the result of:
FCString::Strcmp
or
FCString::Stricmp
My guess is that they are instead relying on the platform code to do its job, though I agree with you that a check at the start could work.
Maybe you could put in a pull request and see if the engine team would want to add it?