DNC rules allow candidates to switch out their delegates at-will, for the record. I'm 95% certain this was just the easiest pretext the AR Democratic leadership could find to attempt to force a unanimously Obama delegation and that this requirement could be at least partially waived or loosened if they wanted to.
Hmmm ... it seems like the Democratic Party is becoming less democratic all the time, doesn't it?
This reminds me of when Democrats were filing lawsuits keeping Ralph Nader off numerous state ballots back in 2004.