Our own spacecraft slow down when they reach their target. We’ve been observed. How do you know how fast it’s moving now? You seem to know a lot about interstellar spacecraft. Are you an alien?
So you are proposing that it was just pretending to be a natural object by slowing down to a crawl while passing by, then sped up again? Wouldn’t have been much simpler to give the thing a very low albedo so that we wouldn’t notice it at all?
First you say that the spacecraft used the sun to boost it’s speed. Now you are saying that it can speed up and slow down independently? Can you say a single coherent thing and stick to it?
Can we stick to the subject of this thread? This isn’t about oumuamua, it’s about Tabby’s star and now a similar star that’s been discovered. I’m pretty sure there’s an oumuamua thread if you want to discuss that. If there isn’t you can start one.