It wasn't well cited, but I believe the point is to ask (rhetorically): how can we keep Syria off the HRC if we can't even get an on-the-record criticism of them by the UN?I believe OP posted wrong link which is not related to Syria's acceptance in Human Rights Council.
Well that's a nice sentiment, but it just plain isn't what the HRC is for. The HRC's mission is to advance the cause of human rights and having on it a country that doesn't have any concept of human rights can only undermine that goal globally even if there is a small chance (I doubt it) of advancing the cause for Syria. Being on the HRC means they'll have the opportunity to make policy statements and write rules. It would be extremely bad for the world if Syria was writing the rules on human rights.I don't think Syria "must" join the HRC to learn something. I see it as a part of involvement in the international community. More involved Syria is with international community, more it depends on international community, easier it will be to see reforms in it. Isolation and condemnation of it cannot improve things.
As arildno said, despotic regimes don't typically respond to cajoling. Their power is based on force/conflict and they typically only change when shown force (see: Ghadaffi a decade ago)..... if at all. As we've seen with the current conflicts in the ME, more often than not, they'll fight just about to the death to keep their dictatorships.