No, that is true, even if it is less directly disqualifying of the specific political tendencies, and the closing of practical horizons of American politics meant that there is a vast demobilization of political action. So, mostly because voting and engagement with mainstream politics is highly correlated with several axes of privilege, white people vote more than non-white, wealthy vote more than poor, etc. So, most mainstream politics and all electoral positions over-represents white middle-to-upper class. There is less of a gender gap on the face of it for parties than one would think because there are a lot of white and women from conservative areas that vote Republican. But there is also a boomerang effect of people that are privileged enough to not suffer ill effects of failure of sabotaged progressive movements such as the Black Panthers and Jesse Jackson's Rainbow Coalition are more likely to vote to the left of the Democratic Party. Because you could get some minor pork-barrel spending if you support the establishment over progressive candidate that will just be crushed by the machine or fizzle out due to internal fractures and more minor sabotage.

So, yes they are. Maybe that is 90% of electoral politics, but it is true that Soc-Dems are disproportionately white men. Though that is more of mainstream politics over-representing privilege on many axes. And also if it is divorced from daily struggle and immediate issues (as mainstream politics works to alienate us from), then politics becomes horse-race stuff for nerds.