I think word lists are copyrightable. The selection is a matter of choice, not simple fact. Note that Feist applies only to the US; phone directories may be copyrightable in some countries.
Compatibility with the GPL is not an issue here; the dictionary is legally a separate work from any program. The real problem is that this license is too restrictive--it is not free. It does not allow distribution of modified versions. In fact, it does not allow distribution of the word list without the specific software listed! If someone asks them to change their policy, they might be convinceable.