It sounds like the John Loder you refer to was the John Loder I have record of. He was born in 1698, son of Edward and Sarah Loder of Somley in Wiltshire, England. He came to New Jersey in 1722 (?). He “Acquired considerable property in Somerset and Warren Counties.” His wife’s name was Johannah ——? He died in 1774. His children were: Benjamin, John (1730-1816), James (I assume this is the person your entry refers to), William (1740-1817) and Catherine (who married an Issac Smith). William was my great-great-great-great-grandfather. He was the uncle who took the guardianship for the children. He also lived in Sussex County.
Old family tradition indicates that the Loders in New Jersey were Tories. That might explain why some moved to Ontario.
Supposedly the arrival of John Loder in New Jersey was recorded in Somerset, NJ in 1732. Have you checked the county records there?