The RDA can't do physics

[Human No More]

We also just dumped a huge amount of heat into the soil, what with the fairly large explosion the impact produced. Anyway, this is an engineering problem the RDA can face when they decide this is a good idea. AFAIK, we don't have the time or knowledge to go into it here.

You're right, it's an engineering problem, which clearly either proved impractical, or a lower priority.

Which is why you don't try and turn it towards Mars, War of the Worlds style. You just shift it in the gravity well so that it ends up on a collision course with Mars, which takes far, far less energy.

Depending on the course, also decades to centuries

It may still be physically impossible, but neither of us have the engineering ability to know that, so I'm giving the benefit of the doubt.

...then why bring it up?

This applies to all materials and to all structures. (Except when you get into mega-engineering, but you're not about to tell me that Hometree is made of carbon nanotubes. )

Again, a column of a given thickness and structural strength. Hometree is a LOT smaller than human structures, which use much smaller structural cross sections.

What is it going to be based on, if not the Meisner effect as generated by Pandora's magnetic field?

It is the Meissner effect, which is different to the normal repulsion between two simple dipole magnets, as I already said.

...This should also be impossible. The core should be pretty isotropic in all directions.

Earth's varies by as much as 2-3x the strength over different areas.

We could discuss only the film, rather than the expanded canon, but I don't think that's what you mean.

I mean that you mistake consistency for possibility in the current day. I would bet Dr Who is consistent, despite not following real physics. Star Trek is consistent despite following something between realistic and implausible physics, but it always woks the same actual way.
Nothing in Avatar contradicts itself, if we take all data about the state of things from the film itself and not from 2011. You've been continually complaining about how it is 'not consistent' without even understanding the definition.

Consistent:
(logic) Of a set of statements, such that no contradiction logically follows from them.

Plausible:
Seemingly or apparently valid, likely, or acceptable; credible: a plausible excuse.

Things that are not plausible beforehand have happened throughout human history as understanding has improved, but hat does not make the reality inconsistent.