Because TP.com is frequently incorrect and simply preys on easy-minded Disney tourists to fork over valuable cash and subscribe to their nonsense. TP uses previous years' performances (although they have no inside track into Disney's actual numbers - Disney does not release this info to anyone) and they pretend to use it to "predict" upcoming traffic. Ever hear the expression "past performance is not indicative of future results"? That describes TP perfectly.
To answer your question specifically, that week will be very heavy with occupancy and attendance at WDW. Pay no attention to TP.com. They are wrong as usual. There are many events and conventions taking place in WDW that week, not to mention it is the week prior to Halloween with
MNSSHP and
Free Dining, etc. It will be very busy. Ignore TP.com.