Has "left" organizations such as the Democratic Socialists of American (DSA) been taken over by subversive agents paid by Empire-serving NGOs and directly from the government? Well, the authors provide well-documented facts that suggest this is so. That reminds me of one of Lenin's insightful quotes: “The best way to control the opposition is to lead it ourselves.”
However, I think the article overstates a typical anti-Trotskyist views by painting them all with the same brush of cynical subversion. Although I don't agree with everything that the group behind World Socialist Web Site publishes, but they are a genuine followers of Trotsky, whereas the groups and organizations mentioned in the article fit the insight attributed to Lenin, but being applied by subversive agents of the US ruling class.
The 2019 Socialism Conference, like its annual predecessors, combines calls for radical economic democratic transformation and progressive social progress with the demonization of independent foreign governments that are targeted by the US government for regime change, such as Nicaragua, Cuba, Syria, Iran, China, and Russia.
The schedule of panels on foreign policy and international issues features a veritable who’s who of leftist regime-change activists. There is even a talk devoted specifically to demonizing the anti-imperialist left.