Imperial autocracy is almost irreversible. To actively strengthen imperial power for the sake of implementing reforms would mean that once the emperor turns his slaughterous hand toward oneself, it would be very difficult to muster the power to resist.
Hence, there are ultimately only three outcomes.
While the current emperor is alive, he realizes something is amiss and ruthlessly purges the chancellor.
After the current emperor dies, the new emperor detects something is wrong and with ruthless measures purges the chancellor.
The old emperor dies, the new emperor ascends the throne, but temporarily fails to take action; once the chancellor passes, he will then use even more ruthless methods to purge the chancellor's descendants and all of their factional followers.
Viewed from a longer-term perspective, ascending through such means would have an extremely bad influence on the court's climate.