I offered some thoughts on this in reply to your earlier posting on this subject.

The record for John Thomas Cain is taken from the IoM FHS transcript of the Braddan Burial Register.

Several possibilities.
The transcript is in error - check the register at Manx Heritage. The burial Regiser often contains a reference to Death Register.

Have you checked the Index to Registered Deaths - it may have been registered some considrable time after the death.

The name may have been entered incorrectily in the Index or even the Register.