The local colonial elites have little reasons to like the communists though, and the FBU can play that up.
I've always thought the real weakness of the FBU, assuming the UASR does not turn into a scary dystopia, is that there is no rational reason for the working people of the developed European core of the FBU to put up with capitalism when they can see a decently free, comfortable, democratic and attainable socialist alternative works fine. It makes the most sense if the FBU is in fact deeply totalitarian, and information is rigidly controlled, and the degree of social terror brought to bear on dissidents is tremendous. The idea that it can buy off the working classes by welfare and regulatory reforms really puts the capitalists themselves at such a disadvantage in so many ways, I can't see the system holding the Red wolf from the door for very long; the level of taxes and regulation required would undermine the legitimacy of market capitalism even among the capitalist owning classes, and notably even more among the hired technocrats who actually run corporations.
In the former colonized nations it is actually easier to see how capitalist hegemony is upheld; there the task of building up grossly lopsided economies shaped by the demands of the industrialized European core is daunting, standards of living are so low that it would be relatively easy to scare people with some modicum of privilege into closing ranks to resist radicalism, as long as the old European racist system is relaxed in favor of coopting these local elites. But of course successfully impressing on the "middle" classes that their comfort and status depend on supporting the pretenses of private property is another way of saying these classes are coopted into totalitarian--or if one wants to indulge the hairsplitting of people like Jeanne Kirkpatrick, "authoritarian"--mindsets. The masses can be turned against Red militance in various ways, by religious traditionalism (but that piles up the kindling for some kind of theocratic reaction!), by low level cooption into the lower middle classes and the credible promise of this kind of success for the most serviceable dangled before the working classes, by scaremongering, by bloody shirt waving insofar as the Reds do come into conflict with soldiers and police recruited from the working classes. But many of these techniques can boomerang and unless again the living standards of working people are kept above certain thresholds of misery AND are seen to be credibly rising, they will be stretched. One very key factor that keeps workers in such poorer countries in line is that the machinery of repression need not be maintained solely from resources squeezed out of these same people, not directly anyway--OTL the capitalist powers kick back a certain share of the profits they skim off Third World nations in the form of "military aid" and "security assistance aid" whereby nations are given credit and access to high tech weapons and police methods, their paramilitary agents of repression trained in Northern facilities, "advisors" and Northern intelligence agencies horning in and giving their client states advice and direction as well as the means of repression.
So it comes back to the FBU core again. The FBU leading developed nations must pay for both large welfare programs and other means of distracting their own working classes, and divert still more resources toward a carrot and stick strategy of similarly keeping order in much poorer countries too. It is quite a juggling act and meanwhile if any of the less well off people in either the Third or First World FBU sphere can travel to the UASR or even the Latin American Comintern nations, or even as this ATL is being reformatted toward, the Soviet branches either, they will see a much more enticing picture than the gray and scary Stalinism of OTL. It might be possible to persuade people "hey, the USA was very rich before the revolution, they can't possibly afford to spread it around to the whole world," but the trajectory of Red Latin America will gainsay that. And the level of taxation required to maintain a competitively tranquilizing welfare state and the higher standard of living for the working classes this will demand will weaken the commitment of people from middle class strata to the idea that they will surely lose if Red revolution triumphs. And if in fact hard repression, even in limited and apologized for forms, against subcategories deemed somehow deviant and exceptional only, is undertaken out of necessity, then the moral standing of the FBU system as somehow founded on a more just order suffers erosion in the higher levels, and sows dragon's teeth of quite bitter, committed opposition among the targeted scapegoats who truly do have nothing to lose but their chains (and whippings).
