DY raised an interesting point. How would this man in the OP have preferred the world to be created? What does it mean a world without suffering? Who defines what is suffering? Isn’t that subjective? To give a simple example- a woman suffers during childbirth (actually this is a consequence of Chava’s sin, world was not meant to be this way). Medical data says that labor and the accompanying hormones are good for the baby. So one person’s suffering is another’s good. Or perhaps he means a world where he does not suffer?
No death? well, the world was created without death, but Adam messed that one up.
No illness prior to death? Or old age? That too was part of the original nature of the world, but the avos requested that there should be warning before one dies, hence old age and illness.
No premature death/painful death/murder? Doesn’t that have to do with our actions?
Much of the suffering we go through is because of other people’s actions. That is a consequence of the fact that people have bechira, and Hashem allows them to act through that bechira. So perhaps the man’s problem is why there is bechira to do bad, but that is a different discussion.
His arguments are flawed. Suffering does not mean Hashem is cruel, Chas V’shalom, or that the world was supposed to have been created that way. so his conclusion that it must mean there is no G-d, chas v’shalom, is wrong. Methinks he left not for an intellectual reason, but out of emotional pain, and intellectual answers will not make him change his mind.