I DID NOT say you can work "permanently" without a resident permit.

And neither did I, I wouldn't make such a foolish statement, or indeed imply it by using other words, under any circumstances. I'm not an idiot!
As for your advice, not only does it conflict with what the US Embassy states on their website, but also with what the Middlekingdom site says. Having said that, up to now, I have never had any qualms teaching until my RP has been made available to me in person within 30 days of my entry date into China on a Z visa. But that's just me, not the other poster who initially stressed he was not prepared to teach illegally under any circumstances. He can do as he pleases, follow your advice, or other advice on the matter, and any other readers can do so too. I don't care about it at all. However, I wouldn't give such conflicting advice re the matter of teaching legally in China, as you have done, in case somebody followed it and subsequently got into trouble on account of having done so. I wouldn't want something like that on my conscience!