Apologies for the attachment. (I tried to keep it tiny.)
Is this what you're describing? (Notice the very slight overlap between the small and medium pieces.)
This feels like an unintended consequence of the definition of a unit. Maybe change the definition to "a group of connected pieces, at most one of which is both grounded and non-poised"? It's less ambiguous, and I don't think the 5/5 supergroup would be possible that way. However, nests would now be basically unacceptable (trees are still cool).
Also, if you add the term "overpowering" (meaning something like "having more offensive points than one's opponent has defensive points") to the definition section of the rules, the scoring condition becomes a lot clearer (If your predator isn't overpowering you and you're overpowering your prey, you score.)
(My inner refactoring nut is awake now.) Come to think of it, isn't your total offense/defense just your number of offensive/defensive pips, plus three, minus the number of groups? If you define it that way, you don't technically need the "plus three" part in the definition (since relative scores don't change), nor do you need the definition of a single unit's offensive/defensive rating at all.
Description: PNG image