A rebuttal to the “baptism in blood” proof text

This is from Zwingli’s treatise on baptism.  He is responding to those, be they Anabaptist or Romanist, who say that baptism is necessary for final salvation.  The obvious response to that view is the thief on the cross (which is also problematic for “purgatory”)–he wasn’t baptized.   Traditionally, it has been argued that he had a “baptism in blood,” meaning he was martyred before baptism and his martyrdom counts as a baptism.    Besides the rather crude Pelagianism in such a position, Zwingli points out the obvious fact:   the thief wasn’t “martyred” at all.  He was put to death because of violent crimes against the state (which 1 Peter 2 condemns).   Now, the “Baptism in blood” theory could very well be true. I am not arguing against it per se; rather, I am showing that the proof-text used for it will not work.