FlyerTalk Evangelist
Join Date: Nov 2018
Location: Istanbul, Turkey
Programs: TK Elite Plus,BAEC GGL,ITA Executive, AFKL Gold,QR Gold,HH Diamond,Bonvoy Gold,ALL Gold
Posts: 14,185
Probably, the QR Support Twitter team misunderstood your situation, you are never protected on two separate tickets unless you have travel insurance that covers so.
You would probably be admitted onboard at JNB if you show a copy of your onward ORD ticket and most likely a supervisor would able to thru-check your bags to Chicago, however, in case of a delay/reschedule, etc... which would lead you to miss your ORD flight, you are not protected at all.
However, the written statement could help you that you were misinformed by them.
And, please do not forget to report back your experiences after you travel.