I agree with Thoul.
He used that before the fall of technology... and besides that
“Cryogen” was out-of-date for Lutz the moment he saw that new protectors could do the job... and if in 1000 years after PS1 they appeared, in the next 1000years (PS4) there would be other ones... so what good would be watching over Algol sleeping inside a box
when he could have his memories always active inside a ball being able to choose the proper lutz when needed? He knew waking up once every ten years was not enough... he needed new lutzes watching over Algol and developing their skills during a significant and consecutive amount of time.