So if we want true equal rights, and if we are saying that the zygote is not a human being, the men should have legal rights to renounce to the zygote or the baby the same way the woman has the legal right to not only renounce but kill him.
So in reality, this not only gives women the choice to have the baby or not, but forces men into paying for something they never agreed upon.
Well, no.
The fetus, and later baby, is a result of their joint action. Both the man and the woman are responsible.
If the woman behaved unreasonably in a way that created extra cost for the man, then we could potentially say that he's not liable for that extra cost. For instance, if she decided to buy the baby a solid gold crib, I think any reasonable judge would say that the man should only pay half the cost of a standard crib, not half of what the woman paid.
However, both aborting the fetus and carrying it to term are reasonable responses to the situation, so neither one implies that the man is released of his responsibility to pay for half.