I thought it took only a simple majority to change the senate voting rules...
I think the point is that there are a few RINOs who would not support the Constitutional Option, thus eliminating it as a threat in a 52-48 or 51-49 Senate.
The problem has been that of those 55, at least 3 Republicans were on record as opposing the banning of judicial filibusters. Which brings us down to 52, and then several more were uncommitted based on the reasoning that in the future, Republicans might want to filibuster at a future time when Democrats again have a majority in the Senate. So it would have been a tight vote, and will be even tighter if they ever get around to deciding it.
Yes, but you had a handful of GOP senators who might not want the rule change like McCain and Hagel. Most thought a rule change would be tight, right at the 50 mark.