The burden on proof is on those claiming he does exist, because it's really hard to prove a negative
He could also exist but not be the son of this couple. Are there any sources on these trees? Did "Goyer" have any children, supposedly? Since the only evidence is multiple trees, it's most likely a single mistake, copied by a bunch of people who don't check sources.
Most often this happens when someone misreads a source and takes nicknames/alternate names for children as evidence of additional children.
For example, John Phare dies and his surviving children are listed as Agnes, James, and William.
Then when his wife Agnes dies two years later, her surviving children are listed as Ann, James, and William. An incautious researcher might assume this meant there was both an Agnes and an Ann, instead of recognising that Agnes and Ann are likely the same person.
