> a non-profit organization
> should be taken into account when comparing the goals and motivations of organizations developing various other communicators.
Business or funding models can change for both for- and non-profit organizations. Especially as people move to options that are believed to have better user-privacy, the idea that they do not sell/monetize collected user data today does not indicate what they will do tomorrow.
Unless users have strong evidence that companies are not collecting and/or monetizing this information (which as the OP pointed out, there is for Signal as found in a subpoena), the "billboard" approach towards promising user privacy via marketing and PR is a shallow one at best for non-profits as well as for-profit companies.