I have no idea what you mean by "right wing." A right wing in the bourgeois sense? Or right wing in the Marxist sense, as Bukharin's Marxism in the 1920s. Furthermore, it is anti-Marxist to extrapolate Schachtman's cold-war politics from the theories he held in 1938. CLR James was a "state capitalist" but never ceded an inch to the bourgeoisie. His cothinker Raya Dunaskaya founded the group News and Letters and they have been around for decades without ever cozying up to the American bourgeoisie.
The only explanation for the rightward shift of Schachtman is the same as it is for Stalinists who became apologists for US foreign policy (Jay Lovestone, Whittaker Chambers, etc.). Bourgeois society exerts powerful class pressures, especially on those people who are part of the intelligentsia.
I used to drink at a bar near Sheridan Square with an old friend Nelson Blackstock, who was editor of the Militant at the time. The place was a hangout for working-class boozers, who had leftist politics. Most were in their sixties and many had been in Schachtman's Workers Party. They were ideologically frozen in amber. They hated the Stalinist "ruling-class" and the American bourgeoisie equally. This was not a group who would end up with subscriptions to New Criterion. And this was twenty years ago. If I stopped by this place today, I'm sure I'd find the same bunch of drunks cursing the bourgeoisie. How'd they'd analyze the current situation in the former Soviet Union is a different question, since now there is genuine capitalism taking root.
In any case, Solidarity seems to have taken the right tack on these sorts of questions:
"There is another, more subtle error which has exacerbated the tendency toward splintering of the revolutionary left. We believe that it is a mistake today to organize revolutionary groups around precise theories of the Russian revolution. We want to be clear about what this means.
"Precision, clarity and rigor are the highest of virtues in developing theory and historical analysis; however, lines of political demarcation do not flow in a mechanical and linear way from differences of theoretical interpretation. Such an approach leads to unnecessary hothoused debates on issues where long-term discussion would be more in order. It also contributes to the dynamics of factionalism and splits, which in any case have been too high owing to our history of misassessing the political realities of our own society.
"In seeking to overcome this negative legacy, our new organization brings together currents and individuals with a variety of views on theoretical and historical questions, from the interpretation of the Russian Revolution and its leadership to the struggle in Central America today. We will carry on discussion and mutual education, making no public pretense of monolithism and seeking to learn from each other's views... "
Louis Proyect (http://www.panix.com/~lnp3/marxism.html)