Well, if it is intended that they gift Pgens back, I have never see it happen. All ive seen is once they have been gifted to someone, its permanent. I think the replay I just gave you should show this. And if they are gifting them to me, I am unable to gift them back. I believe that is something you would have coded into the AI, to not allow a player to gift them anything. If I notice they have given me something, I will usually control K them. I still think you should remove PGEN gifting at all.
I watched that replay back today and I saw that the red AI actually built 3 smd's(EDIT: Actually they built 5 of them which were all destroyed by artillery and then they promptly built 3 more! After which they got hit by a nuke and died...) and they were turning them on and off repeatedly. Definitely needs a change.