Why is MutexHandle::lock() non-blocking by default?

Just noticed something extremely weird. MutexHandle::lock is defined as such:

bool lock(void *mutex, bool blocking=false)
   {
      AssertFatal(!mMutexPtr, "MutexHandle::lock - shouldn't be locking things twice!");
      
      bool ret = Mutex::lockMutex(mutex, blocking);

      if(ret)
      {
         // We succeeded, do book-keeping.
         mMutexPtr = mutex;
      }
      
      return ret;
   }

but then the code for Mutex::lockMutex() is defined as such:

static bool lockMutex( void *mutex, bool block = true);

What is the handle set to blocking false and the actual mutex set to true by default? It seems inconsistent in my opionion. And definitely gives unexpected behaviour for first time users. I put mutexes around my code, and two threads were still going in. I was at total lost, until I saw that the handle by default is set not to blocking. Am I missing something here?