Dazed and confused.
Join Date: Jul 2008
Location: Dublin, Ireland
The throne might actually be draining what little life remains in the Emperor, be he in stasis or not. Remember what it did to Malcador, one of the most powerful human psykers ever, and he was only on the throne for a matter of hours.
The Emperor, however powerful, was placed on the throne while mortally wounded, and even though he was in stasis, 10,000 years is still a long time if something is leeching your life force all that time.