Platforms set the policies to fit the communities they want to build.
Twitter allows porn, YouTube, TikTok and Facebook do not
Newspaper comment sections will often moderate the word "fuck", while Facebook, YouTube and other will not
There are hundreds of dials you can tune in terms of moderation to adjust to fit the community you want to build. Apparently the Facebook moderation guide is 300+ pages long.
Parler isn't a "free speech platform" - they pretty much have a ban on porn. You'll find that most other "free speech" platforms also have hard limits (usually _stricter_ than what Twitter allow).
Try going onto thedonald and post one of the photos of Trump with Epstein, or Parler with porn, or Gab and curse Jesus[0] in a reply and see what happens
They're not free speech platforms, they're _their_ speech platforms. They have built the ultimate safe spaces for some of the worst online communities.
[0] Gab's own ToS refers to their discretion in removing content and a "God given right" https://gab.com/about/tos