All other things being equal, there is a lot of difference between what an eloquent speaker can achieve and what a heavily accented speaker can achieve in the role of CEO.
This has nothing to do with preconceived bias. This has to do with Paul Graham's examination, over the course of funding over 500 different startups and his experience in that entire domain as a whole, that foreign accents are not desirable. The data is there; your bias prevents you from seeing it because you're misinterpreting it as discriminatory.
As far as I know this all started with a valleywag article a couple days ago, that somehow turned (paraphrased) "Something we've noticed after funding 500+ startups is that people with difficult-to-understand accents have trouble raising money and recruiting cofounders/employees" into "Paul Graham is a racist xenophobe who hates immigrants, pregnant women, and probably non-white people too."
Foreign founders are SOL, no company is going to hire he who will disrupt them out of the market, and those who get in are doomed to menial positions with no change of getting ahead in the company.
The real losers will be local engineers who will be priced out of the market, downwards I mean.
There is nothing preventing people with heavy accents taking a technical co-founder role.
Anecdotal evidence: my father the technical co-founder of a products company has a rather heavy accent while his US born co-founder was the CEO. It worked out decently for them and very well for the company itself: company has been bought for the 2nd time, that is VCs sold it to a conglomerate.