Stein being out of play isn't really so bad since Matt is offline for a week or two.
Besides, Martin's been holding back for mostly OOC reasons. The only thing keeping him bfrom going on a rampage IC is his respect for his family and his reluctance to murder Stein and BIOPilot.
He could have erased all of Terebithia a long long time ago. 
Plus I gave plenty of warnings, this was easily in the scope of what Martin could do, and it was either kill Stein or watch Mithias die.
Instead he finds a 3rd option and gives Stein a new fresh youthful body. Pretty sweet deal if you ask me.