Not really, their target audience is much more likely to hang out on Mastodon and Bluesky. So even if the impressions might be fewer the quality of them is almost certainly higher.
Fair, their post gave a nod to the believers I suppose, and it's reasonable to assume they have different metrics of success for getting the message out to believers vs as they described "The people who need us most are often the ones most embedded in the walled gardens of the mainstream platforms and subjected to their corporate surveillance. Young people, people of color, queer folks, activists, and organizers..."
Having said that, I'd argue that X meets the definition of "walled gardens of the mainstream platforms and subjected to their corporate surveillance."
But, it feels like based on this comment, they should still be on X "We stay because the people on those platforms deserve access to information, too. We stay because some of our most-read posts are the ones criticizing the very platform we're posting on. We stay because the fewer steps between you and the resources you need to protect yourself, the better. "
And view counts aren't available on most platforms, but on tiktok, where they are, they seem to have about 60k plays or whatever in the past 6 months. So, I'm not sure how you can argue that X is de minimus, but, gotta be on tiktok for reasons, that also apply to X, but, X is de minimus and tiktok is not, even though we get many more views on X.
Anyhow, with this response I've spent 10 more minutes thinking about this than I should, I will leave it here with the closing thought that their post feels very disingenuous.