I think the key word there is 'every day person', which for most non-technical people means that they trust someone has looked after the problem, and may actually feel safer by paying someone to do so.
Oh there's no problem paying somebody to do a job. But somehow you'll need to be able to check that the job is done. Or at least read the opinion of somebody who has no stake in the matter to attest to the job being done.
So "the job" here involving making a browser not do things, which you can't see. How often pray tell do you pay somebody to perform a job you can't verify the outcome of, but take him by his word that he did it?
It seems like closed-source is antithesis to "designed for the every day person who really values their online security and privacy."