That is a fair criticism. I think it more accurate to say that as a transitional state it would have capitalist and socialist elements as it becomes less of one and more of the other. Just as,if you were around in the 1200-1400s, you probably would not call the mercantile beginnings of capitalism in Europe capital c "Capitalism" despite the fact that with the advantage of living hundreds of years into the future we can now more clearly trace the outlines of capitalisms origin.

Although to be fair the origin of capitalism was much different since the transition was not always necessarily a conscious one made by a class that understood it's time and place, but more gradual. I suppose the socialist transition away could be much better consciously organised, if you arm yourself with Marxist ideas.