Maybe, without the Emperor traveling around the country and calm downing the people, as he did in the OTL, the GHQ and its puppet government, potentially, could have accumulated enough hatred and hostility, multiplied by famine crisis and economic failure to the point that people would begin to think like, perhaps those militarists were correct to accuse the Americans for conspiring a genocide against the Japanese race after all. And indeed, in this scenario, the GHQ essentially has abrogated their own words of "The ultimate form of government of Japan shall, in accordance with the Potsdam declaration, be established by the freely expressed will of the Japanese people".
If we are to drop out the militarism from the anti-American politics, then surely the communism would be the only remaining valid card here. The post-war Japan was a fertile ground for left-wing politics, and many militarists had no problem in identifying and re-branding themselves as socialists. If the circumstance allows the monarchists to accept abolition of the Japanese monarchy as a fait accompli, what's there to stop the communists from attacking the GHQ's hypocrisy and span the wheel of nationalism, opening up the recruitment pool to former monarchists.
But how could the abolition of the monarchy be accepted as a fait accompli? On this thread, it has been claimed by those arguing the implausibility of republicanism, that the abolition of the monarchy would send Japanese society into convulsion, as a huge part of the population would be horrified at hearing the Emperor is no longer a god. But now you seem to be saying that, for a large number of people, the reaction would just be "Well, if he's not god anymore, I guess I'll just vent my anti-Americanism by joining the Communists".