I'm pretty sure that's just so they don't feel like they have to go all Article 5 on Ukraine. That would be really awkward, going to war against a country you were donating arms to yesterday, right? So sure, there's an agenda, but it seems like a morally defensible one, and not one supported by lies (at least not where it intersects with US interests).

If Russia was not firing missiles at Ukrainian cities, Ukraine would not be firing their defense systems.