I think this is right. It can also be seen in the fact that Foot so often appealed to comparisons between morality and etiquette.
@Banno claimed that this was a mischaracterization, but Foot herself later came to admit that she “made a rotten job” of answering the challenge to distinguish morality from etiquette:
Anyone who thinks about it can see that for human beings thteaching and following of morality is something necessary. We can’t get on without it. And this is the nub of the proper answer to the challenge that I made in ‘Morality as a System of Hypothetical Imperatives’, where I asked why it should be thought rational to follow morality, but not to obey duelling rules or silly rules of etiquette. In that article I myself made a rotten job of answering my own question because, still under the influence of Humean ideas of practical rationality, I thought irrelevant what is now turning out to be most relevant.[15]
[15] It was, I remember, a remark of Rosalind Hursthouse’s in a discussion that put me right about this. See also Hursthouse, On Virtue Ethics, especially chapters 9 and 10.
(Philippa Foot, Natural Goodness, 17)
The point about Banno’s use of Wittgenstein is very similar to this. Banno wants to compare “seeing cruelty in bull fighting” to “seeing the duck in the duck-rabbit,” but he at the same time wants to deny that the difference between seeing the cruelty and not seeing the cruelty is just as trivial as the difference between seeing the duck and not seeing the duck.