If paternity is at issue, it may be that she was told that the judge will defer entering a judgment of divorce until the child is born such that paternity testing may be performed, although if the child will be born in November that really can't be the problem. Or it could be that dad is blowing smoke to try to defer her from filing.

I believe the reference to not being able to divorce after he ships out is based upon the husband's intention to exercise his right to obtain a stay of proceedings under the Servicemembers' Civil Relief Act (SCRA) while he's deployed on active duty.

An annulment is not an easily obtained alternative to divorce - as indicated above, the circumstances under which annulments may be granted are very narrow. A court is not going to delegitimize two kids merely because dad doesn't like the word "divorce".