I wonder if it's just very badly worded - it's listing it as a tree rich in tannins (and hence cocci preventing) rather than specifically saying it's bunny safe, it doesn't appear in the lower list. It does seem an odd thing to have there though, I didn't think oak was safe either.
I feed mainly hawthorn, willow, beech, apple/pear, bramble and wild rose. Virtually all of the forage I give is from above ground level because we have wildies so they eat everything like plantain and dandelion before I can get to it!