“I’d suspect he (Trump) already knows who they are.”
I wouldn’t bet on that. He hired dreadful people starting in 2016. He endorsed terrible people for five years. He’s still endorsing terrible people.
Or, as you say, he “knows who they are” who need to be replaced, but continues to keep and support them anyhow.
Trump is a pragmatist not a purist. He fights the fights he thinks can be won. From further down the field after the first fights are done he refocuses and fights the next tranche.