Alternately, we're legitimately not worried about a made-in-China knock-off of a thirty-year-old design.

Unless you desperately need more government funding. Then you’ll concoct a missile gap or something.

They'll say this initially to downplay the threat, but quickly turn the message back around because they know that "US air superiority is still unrivaled even with the latest developments from foreign governments" doesn't get them funding and doesn't sell planes. Look at how they pivoted with China's stealth fighter:

It’s not the first time a DoD official has verbally shrugged at a key part of China’s military aviation modernization plan. In September 2022, former Pacific Air Forces Commander Gen. Kenneth Wilsbach told reporters that the J-20 stealth fighter isn’t “anything to lose a lot of sleep over.” (The DoD intelligence official today said the J-20 is “still a highly capable system” but one that did not “meet all of [China’s] original parameters.”)

It went from "not anything to lose sleep over" to "still a highly capable system". Notice the bill funding the replenishment of the weapons stockpile after sending the old stuff to Israel and Ukraine just passed so they need to justify their proposed contracts.