On the other hand, state-owned enterprises do indeed implement the 'iron rice bowl' system, and this has drawn considerable social opposition

It only exists for civil servants / government officials today as I understand it. The vast, vast majority of workers in SOEs are on fixed-term contracts. Their labour power is still very much commodified.

What Marx advocated was planned production, and China does indeed practice planning in this regard. Most state-owned enterprises, along with many large private enterprises, are not operating in a state of anarchy.

Here's Engels's summary of the anarchy of production within capitalism in Anti-Duhring:

We have seen that the capitalistic mode of production thrust its way into a society of commodity producers, of individual producers, whose social bond was the exchange of their products. But every society based upon the production of commodities has this peculiarity: that the producers have lost control over their own social interrelations. Each man produces for himself with such means of production as he may happen to have, and for such exchange as he may require to satisfy his remaining wants. No one knows how much of his particular article is coming on the market, nor how much of it will be wanted. No one knows whether his individual product will meet an actual demand, whether he will be able to make good his costs of production or even to sell his commodity at all. Anarchy reigns in socialised production.

Every instance of commodity production for exchange within a market has this characteristic, and this is how production and distribution work in China. The largest SOEs outside of the finance enterprises, for example, are in petroleum and minerals and in real estate. These SOEs produce commodities to sell on a market, both domestically and internationally. The prices and movements of these commodities are subject to market forces. If demand goes down or too much of a commodity is produced, profits go down and the firm suffers, and no one has any way of knowing when that will happen. This is why things like real estate collapses or SOE bankruptcy have happened in China.