First of all, I did not say that proton is opposing capitalism. I said that to oppose capitalism does not mean you have to be opposed to free enterprise. As in, you can be opposed to an economy comprised primarily of capitalist institutions without being opposed to the concept of free enterprise. Proton is simply an example of such a business, which can be used as evidence for the fact that it is entirely possible to start businesses in a free market economy which are actually interested in solving problems as opposed to using the existence of problems as a vehicle to enrich a class of shareholders.
Second of all, “it’s filling a niche created by other companies’ poor privacy policies” is essentially nothing more than a restatement of the second sentence I wrote, which I will repeat here: “I pointed out that as long as it’s a for-profit corporation, it would have not have any financial or legal incentive to continue pursuing its mission if it ever achieved a certain level of market share.”. You’re right that them adopting a nonprofit structure doesn’t change that, but it does change their ability to sell out their customers at the discretion of a class of shareholders, unlike any business which is owned by private individuals.
The irony is, I like proton because I don’t think you should trust literally any business to behave altruistically, including proton. By structuring the business in the manner that they have, I don’t just have to trust them. I just have to trust that the people in charge don’t want to go to jail or get fined, which is literally not true for any business owned by private individuals.