Interesting point.
However, I thought that John is "technically" considered a martyr. When he was boiled alive he SHOULD have died, yet the Lord used this event to convert others -- I was always taught that this made him a martyr because NOBODY could survive without Divine Intervention and John emerged unharmed.
I still feel that because he was the one to witness the crucification, and comfort the Blessed Mother made him special in the eyes of God.
If I am not mistaken (and I could be, I converted in 2005) John is the only gospel read on the Vigil of Easter and Easter.
John is considered "a martyr in will but not in deed" because for one who loves the proclamation of the Gospel of Jesus Christ, Crucified and Risen, and who loves the body of Christ the Church, exile from the community is a fate more terrible than the sudden death of a blood martyr.
The Commites Christi festivals on the Second through Fourth Days of Christmas commemorate Stephen (a martyr in will and deed); the Holy Innocents (martyrs in deed but not in will); and St. John (a martyr in will but not in deed). There is great logic and wisdom to this "Christmastide Triduum"
I remember reading that. John was a very old man when the legend said that he was put in large pot of boiling oil, but came out unscathed. Our God is the God of miracles, and He can alter any physical laws He wants to.