I know similar issue has been discussed over and over again, but can any one please confirm that I qualify under the TWOV rule? (US China Southern phone agent is insisting that I need visa)

Flight 1) EWR -> HKG Direct (UA117)
Flight 2) China Southern HKG -> PEK (CZ309, March 28)
Flight 3) PEK -> EWR Direct (UA88, March 30)

China Southern U.S. customer service is insisting, I mean insisting, that I don't qualify for TWOV because 1) It's reserved under different PNR and 2) It's flown by different airline...

Can I safely ignore this lady and just hope that HKG check-in agents are more knowledgeable about the rules?