"If YOU misread the rules, it's your fault."
Like I posted above, you do your reasonable diligence and read the rules as explained on the DC embassy website. And reading them there, it doesn't jump out at me that you're in trouble on a 72-hour transit if your flight to Beijing first makes a stop in Shanghai.
Can you post a link to the relevant article on the DC consulate website (I couldn't find one)?
Only after reading it, can we opine on the "reasonable diligence" matter.