You will need to run a script that removes the ClanFavor.dCelerity tag on the hero to get this to work. Traditionally speaking, bloodlines only add new disciplines, at least that's how the mechanic worked when the system was originally done.
You'll have to fiddle around with code's timing a bit but you want something like this
Code:
perform hero.delete[ClanFavor.dCelerity]
Since the tag for favored disciplines goes directly to the hero. This should fix your problem once you get the timing on the script correct.