First a note: it's not an embryo until a week or so after fertilization. I'm writing this on the assumption that you meant to say a woman owns her eggs and men own their sperm up until it fertilizes an egg.
If, in this case, the man and the woman jointly signed up for this service "no explicit contract in place" as the article says, they should both have access to the eggs. If the woman alone signed up for the service and the man was only involved to contribute his sperm (as seems to be the case), again "with no explicit contract in place", then the property is hers. In either situation, she should be able to use the pre-embryoes to become pregnant.
I don't think the deciding factor should be if it were an egg or sperm. Again, if we reverse the situation and it was the man who was going for chemo and the healthy woman who donated her eggs to be fertilized (with the expectation that the man would find a surrogate willing to accept the eggs [it's not a perfect comparison, I know]), should the healthy egg-donor be able to claim those eggs simple because the eggs trump the sperm? I should hope not, but, legally, I just don't know.