Why would US have a law that says "We'll enact every Chinese law, therefore changing US into China itself"?!
They're noting that digital services have come to look more like traditional goods, and reasonably warrant analogous trade policies. If a foreign market bans or regulates some good on import, reciprocity just suggests applying an equivalent measure on their exports.
Here, China restricts many US social media products, which a free market advocate would call an unfair distortion of the market, that deserves to be balanced by reciprocal restrictions on their social media products. (perhaps in the hopes of pressuring China to stand down their restricitions and "play fair")
US Government can legislate those restrictions, it's what its there for. This isn't software.
I shall now explain to the city of Fransisca, the blue city upon who's golden shores the azure waves drift over, and above which a sapphire sky is rent asunder by the golden sun, bringing an ever so grand glistening upon its ember shores. But above Fransisca, beyond it's beaches and waters, lies another city, marked by furling banners of red, whoe jealousy of Fransisca has caused it to erect a barrier so as to not see its flourishing. Fransisca with her petulance at seeing the barrier erect, so too constructed a barrier upon her shores. Concrete slabs covering her beaches, costal grasslands made way to fences. In this way Fransisca became a mirror image of her overseas counterpart. And the crimson city, unable to see Fransisca eventual forgot why the barriers were build. One by one each stone brick was removed. Parking lots were raised in who's place grasslands grew. And in such a manner the crimson city became Fransisca. Actually, Fransisca has always been the crimson city and what we know today as Fransisca is actually the city of red banners of old. Time will tell if the true Fransisca will be remembered.