"if a guy gets a woman pregnant, I think that if he makes it clear that he wants an abortion, his responsibilities to said child should be waived/lessened if she decides to keep the baby."
I heartily disconcur. He IS the father, and the child IS his responsibility. He took that responsibility (even if inadvertently) as soon as his semen went into her body, and no amount of wishing can relieve him of it -- legally, ethically, morally -- particularly if the mother wishes to own up to her responsibility and keep the child. If he does shirk his responsibility, then he's abandoning the child and should be treated as such.
As for the anonymous (for now) Australians, I'm not going to get into the legal side of it too deeply. I'm not exactly well-versed in Thai family law -- other than that, according to the NZ Herald, the whole arrangement violated that law, since surrogacy is only legal if 1) there is no money and 2) the surrogate is related to the parents. On an ethical level, I think the child is the Australians' responsibility. If they wanted to make sure they could abort the child if things went wrong , then they shouldn't have used a surrogate. Their right to determine the course of the pregnancy -- other than to insist on receiving back the babies they temporarily gave up once the due date arrived -- should have been restricted. Ordering the woman to follow a particular diet would, I think, have been beyond the scope of their rights just as much as ordering her to abort the child. Her refusal to follow either of these orders, or any others that would affect her person, would not relieve the parents of their responsibility to take the child and deal with him themselves once he was born. They shirked their responsibility, abandoned the child, and should be treated as such.