My thinking is the whole team thing was gone when Vechs went into the nether the first time. After he made that mistake, he tried to get the team to commit to that mistake. Then after he gets back, Jsano goes into the nether. At that point, I would have felt I was on my own as they were unreliable as team members. And when they made the flanking plan and Vechs goes nether hopping again, I believe Genny realized he was on his own no matter what.
Also I don't think Genny thought he was going 1 on 3. I think he was planning on doing some damage and then running back to 0,0. There was some serious lag happening, as Pak's ghost can testify. I think he was targeting one opponent and broght the rest down on him. He should have pulled out after missing Baj when he was riding away. He really should have baled after Pak was ghosting. But I believe at that point Genny might have thought better to go out in a blaze of glory, than return to his unreliable teammates to die while waiting for them to get their heads in the game. You cannot tell me Vechs was playing UHC PvP or he wouldn't have put his "mission" before his team, especially after the other team was spotted in the vicinity.