You could start an organisation to do exactly that and it would qualify.
Being “tax exempt” doesn’t really change much… you can offer a tax deduction to wealthy donors. Most people aren’t that wealthy and don’t care about tax deductions.
You can’t conduct business and not pay income tax on it (that’s Unrelated Business Income, which the article talked about). All you can do is collect donations, grants, etc. and then use that to further your organisation’s purpose.
I would love to see lots of nonprofits organised which have philosophical/political conversations at a local coffee shop once a week!