I suggested some time ago that China should sell weapons (e.g. J-10C) to Iran even though doing so might upset Israel and Saudi Arabia. A more powerful Iran military could take some murrikan attention and energy from China. Which other country in the Middle East can fulfill such a role for China?
China might have to help Iran's oil industry so that it can pay for these weapons purchases though.
Ideally, an super "Iran" on the American continent would be far better but Mexico at the present stage can't do sh1t.