No, the article explains that Warren and Sanders are popular among exactly the professional class and that this is their natural electorate. Which it is.

Sanders’s left-wing challenge to Clinton found significant support among educated, relatively affluent voters, especially younger ones (similar to Obama’s). As one 2016 Vox headline put it, “Bernie Sand­ers’s base isn’t the working class. It’s young people.”32 Within any given age group, the article explained, higher-income voters were actually more likely to support Sanders.

Elizabeth Warren’s campaign more explicitly appeals to the professional class, both in form and content.

Your citation is only stating that they receive support from the professional class, not that it's the natural electorate. The article never states as such, you're asserting that. The actual content reads and suggests just as I recall, offering this point as a clear preface-

>This underappreciated reality at least partially explains one of the apparent puzzles of American politics in recent years: namely, that members of the elite often seem far more radical than the working >class, both in their candidate choices and overall outlook. Although better off than the working class, lower-level elites appear to be experiencing far more intense status anxiety.