The convincing is necessary because Sam has seen enough by this point to understand that continuing is not straightforwardly good — that the network he has built is also a weapon, that the connection he has made is also the condition the extinction requires, that Amelie's cooperation with the mission was not what it appeared to be. Die-Hardman and Amelie asking him to continue is the game testing whether Sam's commitment to connection survives the discovery that the connection was being used.

It does, because Sam's commitment was never to the mission. It was to the people the mission organized — Deadman, Fragile, Heartman, Mama, Lockne, the preppers and porters and survivors who agreed to be connected because connection was preferable to the alternative. Heading back east is not compliance with Die-Hardman's request. It is Sam deciding that the people in the network are worth the risk that the network represents.