MLK also became a martyr in 24 hours.
That happens, when someone so central to a larger movement is assassinated. It is then seen as an attack on the entire group, and not merely an attack on that particular person.
Discussion
It's a part of the psyop. Media crowned him a martyr and a saint for their own use case and they will exploit every inch of it and in the end Charlie and whatever he represented will be torn to pieces.