We don't know the fill briefing but two statements in the article left a lot of room for interpretation.

"… he forecast Chinese occupation of a portion of North Korea or a threat of invasion to South." It can be reasonably expected that China would occupy some border territory in North Korea to stop a flood of refugees flooding into China, but an invasion is another thing.

The article reported:

He said if China decides to intervene after a collapse, its armies will arrive in Pyongyang before South Korean troops get there, and if a battle breaks out, then Chinese forces would have two to three times the quality advantage. Technical assistance from the United States, based on a continued Korea-U.S. alliance would be crucial, he added.

In 1979, when ROK President Park was assassinated, the U.S. and the U.N. already had forces in ROK. Despite what many ROK dissenters say, there never was any international concern that the U.S. would attempt to occupy the country. But, at the same time, the U.S. sent a very clear message to the DRK not to try to exploit the situation and move on the South.

I wonder if the analyst took into account the population of DPK? How would they respond to Chinese troops moving into their capital? They tolerated nearly 60 years of oppression because it was under revered Koreans. The Chinese would only be seen as foreign occupiers. Even in the North, I am sure they have been well schooled in Korea's histories with occupiers. There would be massive and blood rebellions that would insist on an international response.

Maybe this would be the first big international test Biden promised and McCain boasts no one would challenge him with.