Like Trotsky Goldstein (that is, if Goldstein existed at all) was of Jewish decent(Goldstein had a Jewish name and a "Jewish face"). I noticed the image of Goldstein described in 1984 is similar to Trotsky:
“could never see the face of Goldstein without a painful mixture of emotions. It was a lean Jewish face, with a great fuzzy aureole of white hair and a small goatee beard—a clever face, and yet somehow inherently despicable, with a kind of senile silliness in the long thin nose near the end of which a pair of spectacles was perched”
Big Brother was described as "black haired, black mustachio’d", a bit like Stalin. Stalin and Trotsky despised each other of course. Trotsky, like Goldstein was a former top member of the party who was expeled, and became a hate figure afterwards (in Stalinist USSR Trotskyists were made to be seen as fascists.)
Another theory I've heard is that Goldstein is inspierd from the anarchist Emma Goldman.
Personaly I think Goldstein is just a propagandist creation of the party, which they use to trap dissidents.