In "Kuhse, Helga and Singer, Peter. Should the baby live?: The problem of handicapped infants. Oxford: Oxford University Press, 1985," the authors argue in Chapter 4 that there is no distinction between action and omission with regard to moral responsibility. The authors give example of lifeguard who killed a swimmer or intentionally let him drown, and argued that both are morally equivalent.
In p. 132-3 the authors wrote
But what of potential? A normal new-born infant has good prospects of a worthwhile, happy and fulfilling life, a life with many of the experiences which we think of as making our own lives rewarding and satisfying. Does not this potential distinguish the normal infant from the severely handicapped infant and give the former the right to life?
Tooley argues that a right to life cannot be based on potential. His argument is based on a rejection of the moral significance of the distinction between acts and omissions–a distinction which we also rejected in Chapter 4. The relevance of this distinction is as follows: if one holds that it is wrong to kill a new-born infant (or a foetus) because the infant (or foetus) will eventually become a person with a worthwhile life, then why is it not also wrong to omit to do an act which would have the consequence that a person with a worthwhile life comes into existence? In other words, if it is wrong to kill, why is it not also wrong to abstain from sexual intercourse that would lead to procreation? ...
I do not understand how can celibacy be considered an omission? Can someone explain to me the connection in an easier form?
Note. I am only asking about the logical connection, and I am not requesting a refutation to the authors' views.