In the same way that decaf is coffee without the caffeine, (and phone-sex is sex without sex), pseudo socialism is socialism without genuine socialists. In the USA -- and increasingly in Europe -- we've seen the socialists' ranks get eroded by our societies' blind pursuit of ever-greater profits at the expense of the common good. This has resulted in the subordination of most aspects of life -- including most aspects of political life -- to the central mechanics of the market. Politicians cannot win elections without capital, which subordinates them to the capitalists. This is why they routinely support corrosive policies (like hobbling healthcare, turning a blind eye to the opioid crisis for decades, decreasing taxes, regulatory capture, etc) and oppose policies meant to better the public uniformly (like free healthcare, free education, net-neutrality, higher and transparent taxation, independent and effective regulatory bodies, etc). In short, they are obligated to support policies that will generate profits for their wealthy patrons, at the expense of everyone else.
Socialism is meant to be a counter-force to unrestricted capitalism. America lacks this counter-force. Instead, America has a (so called) Left that is afraid of being branded "socialist". Because they cannot embrace genuine socialist policies for fear of upsetting their very wealthy and powerful patrons, they are trying to win votes by appealing to people's pathological tendency to form rival tribal groups. This is quite the irony, considering that socialism's original rallying cry was the (inherently trans-tribal, trans-national)"Workers of the World, UNITE".
True socialism looks for opportunity in horizontal social partitions (the social classes), whereas nationalism looks for opportunity in vertical social partitions (ethno-linguistic and religious segregations). This is why nationalism is the capitalist class's preferred evil -- it directs the dissatisfaction and anger of the lower classes against each other, away from the wealthy. Both the American Left and American Right are focusing on the vertical (tribal) partitions -- it's just that the Left is very polite and composed about it.
This is what (I believe) the GP tried to imply with the term "pseudo socialism".