Something's missing here with the explanation of the wormhole. If someone walked through the earthbound end of the wormhole while someone was watching the one light minute away end would only see the person exit one minute later. The only way they'd see the person exit instantly is if the one light minute mouth of the wormhole was removed one minute into the past. This is the point of of Roman Ring. If it's possible for a wormhole to be created then it's possible to create a wormhole with one end in the past and the other in the future; but for a time difference to exist something would have to be done to one end of the wormhole to cause it, such as accelerating it to near relativistic speeds, otherwise there shouldn't be a time difference. It should be clarified that if a wormhole were created with one end one light minute away and one minute into the past wouldn't violate causality because information would arrive at the same time anyways, but this time difference isn't the default state of a wormhole.
Roman Ring / Discussion
This is the discussion related to the wiki page Roman Ring.