Trump's cybersecurity tsar Giuliani hacked, passwords leaked
scmagazine.com
scmagazine.com
Original investigative report that the linked article mentions. This version gives some more information, including that the leaked passwords were from mass breaches like those from LinkedIn and MySpace, not targeted attacks.
Unfortunately, it's still light on details as to which accounts may have reused passwords, whether the passwords in question were still in use, etc. This would be interesting to know from a "which staffers know what they're doing and which don't" point.
The (scarce) details are anyway enough to understand how essentially it is clickbait, in those massive hacks millions of passwords were found, it is not so improbable that they affected also some of the now appointed people.
As you pointed out without knowing if those people still use those leaked passwords for some accounts they may have somewhere the article is essentially non-news.
I am a bit surprised that Troy Hunt somehow gave such "alarming" statements of purely speculative nature, in a nutshell:
let's say that ... and if ... and if ... potentially we have a problem ...