A succinct summary of the situation is in the Post.
A small group of senators and staffers is expected to gather Monday with the Senate parliamentarian to determine whether a tax on high-cost insurance policies would affect the Social Security trust fund, and whether that would violate prohibitions against altering Social Security through the reconciliation process. Republicans say a ruling on their side could short-circuit the process, but Democrats are confident about their provision. - The Washington PostWhile the essence of the reporting is correct, there is an important subtlety which is left out. The Senate Parliamentarian does not render a "ruling," as in the final say on the matter. The Senate Parliamentarian issues an opinion or advice. The actual ruling on the matter is made by the Presiding Officer of the Senate, based on that advice.
In the case of reconciliation, health care reform and Social Security, as summarized by the Post above, the Parliamentarian could advise the Presiding Officer that an objection to the reconciliation bill on the basis of the Byrd Rule's prohibition on changes to Social Security through reconciliation would be in order. Translation: Reconciliation shouldn't be used because the rules say it can't be used to change Social Security. However, the Presiding Officer of the Senate does not have to heed that advice. Actual rulings on order are the sole province of the Presiding Officer, not the Senate Parliamentarian.
Thus, while a Republican Senator could bring up a point of order against reconciliation on the basis of the Byrd Rule's prohibition on Social Security changes through reconciliation, the Presiding Officer could rule against that point of order (saying that the reconciliation bill does not violate the Byrd Rule, in the opinion of the Presiding Officer). At that point the Republican Senator would, no doubt, appeal that ruling to the floor. However, it would only take 51 votes (not 60) to sustain the ruling of the Presiding Officer, allowing the reconciliation bill to proceed. In a Democratic caucus of 59 Senators, Harry Reid can muster a 51 vote majority for a procedural motion. If he couldn't he wouldn't be able to run the Senate at all.
Thus, the Parliamentarian cannot kill the bill, or even interrupt the process, if the Democrats were willing to allow the Presiding Officer to ignore the advice of the Parliamentarian.