Deliberately using an alternative is a form of protesting.
And it can be, sure, but it's not always the case.
I'm not just using Lemmy until or if Reddit backtracks, I'm using Lemmy because I believe it's the superior platform in many ways and has more to offer.
I didn't make an account here in sign of protest, I made one because Lemmy was suggested to me and I'm liking it better than where I came from.
I'm also aware that many users on this platform would go back to Reddit if they backtracked on the API keys.