Well yea, since also the robots are dead, including Astra, so i wouldn't go against him
There is an episode of this AU in which the Traveler kills astra, and Collector is giving up, but when the Traveler is close to killing him, he refuses and becomes stronger
Famous phrase said by him: "No..... I cannot die, i cannot let you hurt anyone else, no.... I shall not give up, for all the fallen, FOR ALL THE SACRIFICES, FOR EVERYONE! I WILL STRIKE YOU DOWN!"
inspired by Undyne's scene of refusing