What he says is also correct from a scientific point of view; choosing to not have children is specifically choosing to ignore a natural instinct which exists for the survival/progression of the species just so that the individual doesn't have to deal with children.
According to the definition of the word doing such a thing is selfish;
selfish
ˈsɛlfɪʃ/Submit
adjective
(of a person, action, or motive) lacking consideration for other people; concerned chiefly with one's own personal profit or pleasure.
While I don't really care if you don't want to have children it is still technically selfish to choose not to have them.