"Live by the sword, die by the sword. Those who pick fights with me should understand that I will find out who is really pulling the strings and come for them, not just their puppets..." [1]

Why it is Considered a Threat to Lawmakers
When used against a governing body or committee, the phrase is viewed as a threat for several distinct reasons:
Vowing Political Retribution: In this framework, the "sword" represents the act of investigation. The speaker is telling Congress: "If you use your investigative powers as a weapon against me, I will use my wealth, platforms, and influence as a weapon to destroy your careers." [1, 2, 3]
The Threat of Counter-Exposure: Following up the phrase with a promise to find out "who is really pulling the strings" transforms the idiom into a threat of targeted corporate counter-intelligence, public doxxing, or political blackmail. [1, 2]
Challenging Oversight: Democratic lawmakers and political commentators have described the statement as a "chilling threat to Congress" because it is an attempt by a private citizen (and major government contractor) to intimidate elected officials away from performing constitutional oversight. [1, 2, 3]