E.angustifolius is alright to eat if you enjoy raking your teeth over a pebbly stone for a veneer of prune flavored flesh.There are many Cerbera species around even in hawaii but cassowaries have a soft spot for blue ones but humans should not try them.If someone said to me they are overwrought with the desire to race into the jungle and consume blue colored fruit this is how I would advise them.
Don't be tempted.
Not by edible alpinia caerulea
or by blue nuns
or by any quandongs go deeper find athertonia diversifolia a macadamia relative with a magnificent nut.It is rare.
Now why is it not cultivated?