Honestly, i think this update actually helped Xanthe Jr. a lot more than people give him credit. Yeah, he was taking things too far with the twins, but he warned them before hand ("it will hurt, there will be pain and suffering"), but he really did what he promissed: he experimented until it sufice him, and left them to get fully conect, even protecting them (kinda) from Cole at the time.
Had it not being the ending and fuckboy being a fuck up, we might not even have the drama, since they would've been fine. So yeah, he may not have cared if they died or not as long as he got his aswers, but it looked like he would have preferred them to ascend too.