This all comes back to Filibuster. If they don't have the balls to abolish the filibuster, then they don't have 'em to overrule the parliamentarian either. Because overruling / firing her means that they can put just about anything in the so-called reconciliation bill and pass it with 51 votes, which is the same thing as not having the filibuster.

So, they will either have to find a way to put something in reconciliation, or try their luck with republicans on a small bipartisan immigration bill - which ain't happening.