McGrath, the UK is not a totalitarian state! If the law currently stands that a man's obligations as a father cannot be waived, the government (whatever organ of government you mean) presumably can't suddenly change that. There are, I think, two routes for change: parliamentary legislation (which would be complex and not guaranteed of success) and action in the courts (same thing). Until this happens, why should the men risk being forced into fatherhood?

I also feel that, by the same analogy, if denying the woman access to these zygotes is tantamount to forced abortion, then giving her access against the man's will is tantamount to her raping him. In both cases, luckily, the TRUE unpleasantness of abortion and rape is avoided.