The act that they performed this under is the "International Emergency Economic Powers Act" which allows the president to declare a national emergency and take some other actions if there is an:
unusual and extraordinary threat... to the national security, foreign policy, or economy of the United States
It specially says the powers:
may not be exercised for any other purpose
The Powers include:
(1) At the times and to the extent specified in section 1701 of this title, the President may, under such regulations as he may prescribe, by means of instructions, licenses, or otherwise— (A) investigate, regulate, or prohibit— (i) any transactions in foreign exchange, (ii) transfers of credit or payments between, by, through, or to any banking institution, to the extent that such transfers or payments involve any interest of any foreign country or a national thereof, (iii) the importing or exporting of currency or securities, by any person, or with respect to any property, subject to the jurisdiction of the United States; (B) investigate, block during the pendency of an investigation, regulate, direct and compel, nullify, void, prevent or prohibit, any acquisition, holding, withholding, use, transfer, withdrawal, transportation, importation or exportation of, or dealing in, or exercising any right, power, or privilege with respect to, or transactions involving, any property in which any foreign country or a national thereof has any interest by any person, or with respect to any property, subject to the jurisdiction of the United States; and.[1] (C) when the United States is engaged in armed hostilities or has been attacked by a foreign country or foreign nationals, confiscate any property, subject to the jurisdiction of the United States, of any foreign person, foreign organization, or foreign country that he determines has planned, authorized, aided, or engaged in such hostilities or attacks against the United States; and all right, title, and interest in any property so confiscated shall vest, when, as, and upon the terms directed by the President, in such agency or person as the President may designate from time to time, and upon such terms and conditions as the President may prescribe, such interest or property shall be held, used, administered, liquidated, sold, or otherwise dealt with in the interest of and for the benefit of the United States, and such designated agency or person may perform any and all acts incident to the accomplishment or furtherance of these purposes.
Noticeably absent from that list is tariffs. Under the major questions doctrine, the fact that congress did not specifically delegate that power to the executive branch means that it did not do so.
Tamara Rubin is a grifter with no expertise who bought an XRF gun to use to scan random objects as fodder for her blog where she gets money from affiliate links. Her wikipedia page talks about a few of her financial crimes. I wouldn't worry anything she puts out.