So long as a man has voluntarily had sex then yes, he is morally responsible for the resulting child - if one occurs. Even if he has used every form of birth control aside from a vasectomy. Now if he can prove he did get snipped before hand and there was no scientific way he could be the father - then no.
CA law - last I checked - gave an alleged father a very short time frame to change the idea that the child was his - ridiculously short enough that in some cases men who have been able to prove genetically that the children were not theirs have still been on the hook for child support until the child reached majority. In most of these cases the man did not even know the woman was pregnant until the state notified him that he was being punished for failure to pay child support b/c the woman left or the couple broke up and he was never informed that a child was on the way.
So there are times and circumstances where the man should be excused from the responsibility of paying child support, but those depend on proving that he is not the father. IF he has dropped his pants then he has taken on the responsibility of paying for the possible kid - all the way through graduate school these days. So guys - please think before you drop your pants....do you really want to get a night of pleasure at the price of 20 years of economic responsibility?
I think if we could drill that idea into teenager's skulls we might have fewer teen pregnancies. ...... maybe...... I hope.....