Even John Stuart Mill, one of the biggest proponents of free speech philosophy, was okay in limiting free speech when allowing it would harm or cause damage to others. SCOTUS has also explicitly stated that first amendment (gov censorship) rights do not apply to threats of violence.
The reddit execs have said as much through their communications, that they're okay with allowing hateful and biased communities so long as they're not targeting, damaging, or causing harm to individuals.
People are misinterpreting that as reddit being a "bastion of free speech" without fully understanding what free speech really is.