Nah, Yasumi was too much of a goody two shoes for the Gentleman to reveal any plans to her, and you figured it out, afterbirth is an ironic reference to John being Israel's brother, of course Israel just means it to be an insult.
Israel is so funny when he's in denial. I wonder how he'll react when he finds out 'afterbirth' is his little brother? Also, would Yasumi have known about the project? After all, it was an off shoot of the Mewtwo project. Even if she did, I bet she'd wait to tell anyone until the time was right for it to be discovered. Hm... What a mess. :D