Very few American companies are banned from China. The parent's comment is based on false premises about the economic relationship between the US and China.
Yes, China very selectively bans American companies, just as the US is now very selectively banning the same types of companies. It’s just Mercantilism: be open in all ways except the key industries you wish to develop domestically. I don’t think mercantilism is fundamentally evil (it’s how Japan and South Korea became wealthy first world nations at certain American industries expense) but don’t cry when your trade partners bite back.