Another possibilty.
Possibly John was baptised under his mother's name.
Based on 1861, his aunt's name was Elizabeth Cowin.
There is a christening in Lonan of a John Cowin to an Eunice Cowin.
Eunice is in the IGI the daughter of William Cowen and Elizabeth Quayle.
Elizabeth, and a number of other children, appears to be the daughter of William Cowin and Esther Fayle.
There is a marrige in the IGI for this latter couple in Braddan on May 7 1803, but not for Esther Quayle.