The Kneen connection is strengthened by the marriage in her parish - however there is a later marriage of a Catherine Templeton in Braddan. If this was her as a widow then Thomas might have been buried in Kirk Braddan, the published index to burials (and the basis of Brian's index) is now known to be both incomplete and erroneous in parts as it was apparently based on just one burial register but now that the parish registers have been deposited in the Manx Museum it was found that there is another burial register - the indexed one would appear to be a partial copy (one theory is that two books were kept about the time New Braddan Yard opened, one of which was those for whom a service had been held)

There is an a marriage of an Agnes Templeton in Braddan to a William Gill in 1849, but as you say the name is conspicuous by its absence from the IGI - there are a few sightings of name on my site - one is the transportion for gross immorality in 1820 of Richard Humphrey Templeton; It is possible they were Roman Catholic - two baptisms involving Patrick & Susan Templeton appear in Brian's 'Dissenters' index