I will say that I don't think your fictional scenario itself is sufficient for closure, but I do think in this specific instance there is still some troubles with it.
The other meta post you link to seems more concerned with actual published works of fiction that still has well defined rules and things that happened that other people can go look at. The physics in the questions discussed there are assumed to be the same physics we all know and love, it's just in the context of fiction.
In your case you have made up your own fictional scenario that starts off with something completely unphysical. In general, the issue is that this can often involve assumptions that aren't clear, are wrong, or open the door for nonsensical answers. Assumptions might also not be complete, thus forcing answerers to fill in the gaps can causing the question to not have a unique answer. To quote Stanley Hudson:
How 'bout make believe land has anything you want.
In your case some of the fiction is confusing. You said the Earth has disappeared, but you are talking about Earth escape velocities, which wouldn't be relevant if the Earth disappeared. Are you wanting to consider the alterations to the orbit of Mars due to the disappearance of the Earth? Or are you assuming in this scenario that also Mars continues on it's same path?
If you really are interested in real physics, then I would try to find an actual real example to set up your question. This is because you don't need fiction if your question didn't start in fiction (like the other meta post describes). When possible, just stick with what is real so that the question can be as clear as possible and everyone is working with the same physics.
Why not just ask about a possible scenario of an astronaut on a spaceship in a sun-planet system that is wanting to launch objects onto the planet? Then you don't need to bring in disappearing planets.
Although, in my opinion the question is really just asking for a calculation to be done, as evident by the current single answer. So part of me feels like the question would need to stay closed anyway. It seems like you know the physics already, you just want a calculation to be done. You aren't asking about how gravity, escape velocity, orbits, etc. work in the context of physics.