None of this really matters as OP was denied boarding. What does matter if OP has everything correct is that the AC agent incorrectly told OP that his ticket was non-refundable when it was.
OP could have had the ticket refunded, less the $200 fee and purchased a UA ticket via EWR and not had to deal with any immigration issues at all. Needless to say the UA ticket might have cost more, but that is a different issue.