How did Larry Wu-tai Chin's leak in Oct. 1970 — of a classified document — allow China "to alter [...] volume of anti-U.S. rhetoric in the press"?

Question

        In the course of his nearly forty-year espionage career, [Larry Wu-tai] Chin [金无怠] supplied the PRC with information on U.S. intelligence requirements and foreign policy initiatives relating to China, as well as a biographical profile of at least one CIA co-worker, Victoria Loo .¹⁸ In one specific instance he confessed to having passed a classified document to Beijing in October 1970 that discussed President Nixon’s desire to open relations with the PRC.¹⁹ China’s leadership therefore knew about Nixon’s intentions well in advance of his diplomatic overtures. This would have allowed the country to alter its internal and external policies (such as the volume of anti-U.S. rhetoric in the press)[emphasis mine] in order to reap the maximum political benefits.
        As an FBIS analyst and one of the CIA’s few fluent Chinese linguists, Chin was able to pass along such information as Intelligence Information Reports (IIRs) on China and East Asia, biographical profiles and assessments of fellow CIA employees, and the names and identities of the agency’s covert employees. He was also in a position to provide information about recruited agents in China.

Nicholas Eftimiades. Chinese Intelligence Operations (1994). Page 32.

Kindly expatiate the emboldened quote in simple English? I am not intelligent, historian, or intelligence officer!

Did PRC's foreknowledge of "Nixon's intentions well in advance of his diplomatic overtures" BOOST or LOWER "the volume of anti-U.S. rhetoric in the press"? But why? How could the PRC afford this gamble that could have nettled the US?

Couldn't boosting anti-U.S. rhetoric in the press have boomeranged on the PRC? If China heated up its rhetoric against the US, China could rile Americans enough to hinder Nixon from opening "relations with the PRC".

Answer 1

A BBC article on 'The week that changed the world': How China prepared for Nixon, written by an individual who was a student in China at the time, recounts how certain changes were made concerning the type and level of rhetoric allowed, at least directly during the visit itself (emphasis mine).

I was 15 at the time, attending secondary school in Beijing. I don't remember much about the actual visit, and all the friends I have talked with also only have very faint memories.

But we all remember one thing, which is the general stance towards the American visitors that the government had stipulated: "Neither humble nor arrogant, neither cold nor hot."

The article also discusses instructions directly given to media outlets:

Yang Zhengquan, former chief of the Central Broadcasting Station, recalls the general guidance for media reporting being that there had been "no change regarding China's attitude to the USA".

Meaning, "we are still against them, but President Nixon is our guest, so we can't shout 'Down with Nixon' and 'Down with US Imperialists' to their face".

As a result, the "US imperialists" moniker would be changed to "USA" in radio and TV bulletins for the duration of Nixon's visit. Some anti-American content could still be produced but it should not be excessive.

So you can see there is evidence that subtle changes were in place to tone down the level of anti-US rhetoric at the time of the Nixon visit, definitely not to boost anti-US rhetoric as the question originally implied.

Answer 2

This leaked to the Chinese that Nixon wasn't the raving anti-communist, as he appeared to be. In reality, Nixon was eager and earnest in his plan to make a pact with the Chinese to break the deadlock in Vietnam.

At that point, the PRC was isolated economically, under sanctions, not recognized by the UN. Taiwan was still considered to be the Official China then. PRC was pretty much a Soviet puppet state. It was a huge confidence booster for the PRC leadership, to know they could break off with the USSR because the US would get cozy with them.

Without this leak, PRC could never trust Nixon to be honest with his overtures. With this leak, PRC were convinced they could go ahead.