I don't even really think it's that they don't see that point, it's that they don't want the US intervening in any more conflicts because the US always picks that side that's closest aligned with their own capitalist/imperial goals, and the struggle for worker solidarity is the dominant dialectical struggle they're interested in. If the US showed any interest in assisting a socialist project be successful, they might feel more comfortable with the US's involvement, but that's historically not been the case (nor would that make sense in that particular dialectical materialist worldview).