In the current realm, a revocation IS much more serious than inactivation. Revocation means your clearance is removed completely, and should you require a clearance again, you would have to go through the whole process from square one. A revocation would also make it much less likely that the person would be able to pass a subsequent clearance investigation.
Brennan has left the government and is working in the private sector, media no less. Nothing short of revocation is appropriate.