John's spouse's last name was not Steele. It was discovered that a descendent used that name to gain entry to the sons/daughters of the revolution. Wilmoth is not a common name so this person assumed that Steele was the one who married John as it was the only Wilmoth they had come across. Unfortunately this has spread all over the internet and the odds of it being true are practically zero.
There has been speculation that Wilmoth's last name is Dudley - it was common to name a younger son after the mother's maiden name. Wilmoth Dudley appears to have stayed with her husband well past birthing years, however.