Here's my reasoning on why the palace is still (mostly) standing. The post I was linked to was a single paragraph in a three paragraph post (albeit well written). The number of soldiers wasn't stated, but after combat engagements and the like, they wouldn't number super high. The Aldera Royal Palace is a huge sprawling complex with multiple towers, a huge dome, multiple wings, and a guest wing set aside from the palace itself. The group putting explosives would literally require hundreds of pounds of explosives and at least an hour to set them all. The NPCs involved didn't seem to be anything aside from standard front line troops and while I'm sure Helios is an excellent practitioner of Force Sight and a specialist in Archaeology, I don't think he's a demolitions expert or an explosives expert and archaeology only goes so far into understanding the full mechanics of architectural design.
My logic is simple: Helios and a squad or more of front line infantry with only the explosives they could carry (even star wars explosives) would not have been able to set the number and size of charges needed to destroy the entire Aldera Palace. I understand there was probably previous damage to the structure, but let's be honest, this would be the equivalent of 9/11 where the plane hit the side of the building. A tower may be knocked down, a wing destroyed, loads of damage, but the majority of the palace would still be intact. Also, the tanks were shelling the grounds around the palace and the steps of the palace. A stray shot or two, maybe, but the damage caused by teh tanks would be minimal to the building itself.
If you feel differently, feel free to PM me. I'm not out to retcon folks, I'm not out to power game or god mod anything, just using basic, standard logic on an IC issue.