This is probably a fig leaf to China to obtain clandestine support.
This is absolutely a massive behind the scenes deal with them. China's outwardly passive approach to this war coupled with this move reveals that they are doing something serious behind the scenes.
This is Iran giving up their primary bargaining chip to provide an economic advantage to China. Which means China is either giving them nukes (unlikely) or (more likely) providing them with intelligence and equipment that can be used to deter the current aerial campaign.
Indefensible, especially since his whole appeal was being a duck that could handle this shit. He was so good at ignoring this garbage during the campaign. Folding now is so fucking stupid and shows that he was just playing a character for the campaign.