The Wormhole could have been discovered and then stabilized thought this "Arkcon" project/organization.
I don't think we need strong motivation for exploring a different galaxy to be honest. Even though the Milkyway is only 1% explored, if the wormhole opens to a cluster with plenty of resources, mysterious and powerful technology, and a mass of habitable planets, then I would imagine their would be interest to explore and settle it. If the Helios Cluster can be reached relatively easily (through the use of a relay or conduit or wormhole or whatever they come up with), then it just becomes another area like the Attican Traverse. Distance doesn't matter so much when you have "teleporters".