“Has someone got an explanation for why I should see it differently?”
They really are apples and oranges. The interceptor missiles are small and have no warhead. They just hit the target and use kinetic energy to destroy it. It is not going to be mistaken for a ballistic missile with a warhead which would be much larger.
The problem the Russians have with it is not that it might be offensive but that they think it might actually work defensively and that diminishes their nuclear threat.
That's partly true but it doesn't stops here. The continuation is that the Russians believe the USA will attack Russia with conventional means when they see no threat in the Russian nukes.
Thanks James.