The egg has a full set of mitochondria and ribosomes needed to launch the normal rapid division process that is initiated by fertilization. Swapping out the nucleus leaves all the "machinery" in place for a new set of DNA from the "mother" copy. The "father" copy needs to arrive followed by an acrosomal reaction to lock out entry of a 2nd DNA source. There is a possibility of mistake in this shuffle for humans. Putting 2 Y chromosomes and zero X chromosomes would not be viable.
The lack of ethics behind this process was one reason I left the field and pursued making a living in the EE/CS world. Too many amoral researchers doing things that should never be done, but proceeding anyway because it is "possible".