A cow using a scratcher is doing something that provides an immediate reward. The cow that selects and manipulates an appropriate stick is planning ahead for a future reward.

I think they make a distinction between acting on an object and merely using the environment. The first requires more agency, I guess.

thing is, if you call that tool usage then it's also tool usage to.. do most things, really. Is it tool usage when chinchillas take dust baths to clean themselves?