The subject of the quote is Creolistics, not the definition of Creole. If you are looking for scientific definitions of linguistic categories you are going to be very disappointed. Language involves humans. Language is messy.

As well, any question that involves “meaning” must itself answer the question “to whom?” I answered from the perspective of (some) linguists, but as another user pointed out, non-linguists might very well and with no ill intention consider it an appropriate term.