Yes free expression obviously does have limits; It probably doesn't have that silly "Fire in a theater" restriction.

Holmes (the supreme court justice you are quoting) said this with respect to this case: https://en.wikipedia.org/wiki/Schenck_v._United_States where they prosecuted Schenck for anti-war pamphlets. This is something that would be protected by the constitution today. This quote is a pretty lousy excuse for suppressing free expression considering Holmes's track record of dismissing free speech.

With regards to Facebook removing posts, why should there be a "due process" for a (specific) company to remove posts. What sense does this make?