It's not the senate generally that is taking the parlimentarian's advice in this case, but the presiding officer, who does get to unilaterally decide (although

It's not the senate generally that is taking the parlimentarian's advice in this case, but the presiding officer, who does get to unilaterally decide (although the have some options). See 2 USC 641(d) for it being out of order and Senate rule XX for how those are decided (which is surprisingly flexible, as you hit). Or for a more readable source: https://www.cbpp.org/research/federal-budget/introduction-to-budget-reconciliation https://www.cbpp.org/research/federal-budget/introduction-to... But the fact that we're even discussing this shows that the article is pretty reasonable in calling this arcane.