I had to look this up

Apparently the phrase on the podium is real rathe than faked.  And it appears to be an official Homeland Security creation:

The podium sign link leads to the "Worst of the Worst" page at the Department of Homeland Security, but the phrase is not explained there.

The obvious implication would be "if you do something bad to our people, we will do worse to all of your people" but the historical context was unfamiliar to me.  Googling the phrase resulted in lots of hits.  There is a very detailed commentary at the Ask Historians subreddit; here is an excerpt -

Several variants of this post are going around online, and the majority of them seem to attribute this supposed Nazi quotation to the Lidice massacre of 1942, which was committed by the German occupation authorities in the 'Reich Protectorate of Bohemia and Moravia' in response to the assassination of the deputy governor of the province, Reinhard Heydrich, by British-backed Czech commandos in Prague ("Operation Anthropoid") on 27 May 1942. Heydrich survived the initial attack, but later succumbed to his wounds on 4 June. The (unfounded) suspicion that Heydrich's assassins had been given shelter by the villagers of Lidice led to that village's siege and subsequent sack and destruction on 9 June 1942. All male villagers aged 15 and up were executed by German forces, whereas female villagers and underage boys were fed into the concentration camps, mainly the women's concentration camp at Ravensbrück.

So this is where the "One of ours, all of yours" supposedly comes from: "[You kill] one of ours, [we kill (or capture)] all of yours". And that's where the history ends — because that phrase was never used by the German government. The Lidice massacre was not something that they particularly propagandized [EDIT: they did issue public statements notifying the public that the town was "razed to the ground", the women "interned in a concentration camp", the children "transferred to suitable institutions"; though my point was that they didn't make up fancy catchphrases to propagandize the deed.], and propaganda directed at the villagers was unnecessary, because they were to be the victims of armed force anyway. The young sketch artist and famous Holocaust victim Petr Ginz only noted the Lidice massacre in his diary on 13 June (four days late), implying that there was an information delay (through the rumor mill) that there definitely would not have been had Lidice been widely and purposefully advertised. 

There are more comments from other Redditors at that link.

There are other links, but what I have not seen is an official declaration from the Trump administration on why the phrase was chosen and what implications are intended.  If anyone sees such on Truth Social or such, please add a comment to this post.