I don't know why people keep looking at this as China helping Iran. China isn't in the business to hand out charities, it would intervene in Iran for its own benefit. Iran would benefit too, but they'll have to pay for it as I listed already in my previous posts. The deal can work because in that case the interests would align. If they don't then China won't intervene, as it hasn't at least not overtly.
Just to repeat my reasoning for Chinese intervention. In the event of AR, the expected Western response is a blockade far from Chinese shores in the IOR. China does not have the expeditionary force to contest this effectively, it will need to rely on land links to help "port hop" its way west, and Iran would be a key part of it. Now, do you think it's easier to do this now or wait until US troops are entrenched in Iran with the backing of a puppet government?
That is why China should relocation some H-6 bombers in Pakistan. These bombers have missiles that can destroy US naval assets in the region.