Yes, but not any old noble gas. Helium and neon, for example, have higher thermal conductivities than nitrogen. So it seems like argon is better for the job as

Yes, but not any old noble gas. Helium and neon, for example, have higher thermal conductivities than nitrogen. So it seems like argon is better for the job as well as being cheaper. (While every noble gas has roughly the same heat capacity by mole/volume. Perhaps some CFCs would have been even better for insulation, but bad for the ozone layer, of course, and rightly banned?)