My reading of the slide is that they're making the distinction that it's an action (verb) not a state of being (identity), similar to the meme that "human being" is an action rather than a thing.

I take the following sentences as confirming this reading:

> Being a marginalized person takes no action - it is an identity:

> Acting as an ally is about action - it is not an identity, which is why we talk about "ally skills" instead of "allies"

> Depending on what is most relevant about you to the situation, you may switch between being marginalized and acting as an ally