Wrong. I planned to take advantage of the 72 hour visa free entry when flying into and out of Beijing. But Chinese Immigration keeps records, and my previous infraction made it impossible for the desired visa to be issued. Problem.
Thanks to wonderful customer service by Singapore Airlines staff who were very effective and persuasive with the local officials and ticket agents of Air China, we were able to avoid having to return to Singapore, instead flying on to Mongolia on the next available flight. Cost of overlooking the past? About $1500. Ouch.