@Doc I would say no. I don't have experience with magnesium cement. Further, adding aggregate will collapse the mix. So I thinking refractory air cement is not possible unless you make it with lye and aluminum powder, but then it's not aircrete and doesn't require the little dragon.
However, after the structure is up you could paste on lava stone or actual refractory cement. If fire is the primary design consideration then perhaps an underground structure is the better option or tall earth berms. You could also engineer a battery, pump, water tank sized to burn times and BTU exposure and spray cool it.. Live in field..
I suspect that are aircrete would actually survive a fire but even if it didn't the whole point of all this is cheap housing right?
Now I'm rambling...