Terms of service are pretty much the legal equivalent of graffiti, they are there to look impressive not mean anything. You'll struggle to find any legal rulings based on business to consumer TOS because companies know they are very like to get rejected as unenforceable due to discrepancy between the parties and inability to negotiate.

If reddit are asserting control of content by forcibly publishing it (opening private subs and undeleting comments) then there is a very good chance a judge would see them as being responsible for it.