Orbital Bombardment?? Where's it say that? I read about the Snow birds not helping and being paid off. When did Caleb the magnificent allude anything to Khan McKenna??
ER3145, pg 34. The DCMS's PWS bombarded AFFS troop concentrations on the planet's surface before the actual Co,bine invasion began.
Why not go straight for Luthien and New Samarkand? They could go through uninhabited systems so they won't have to go against the DCMS to deliver their nuclear cargo.
Because the Combine are yet to do anything that warrants that level of escalation of the conflict. Yes, they have inflicted staggering levels of losses on the AFFS, but they haven't used nukes or other WMDs as yet. This has been fought as a late Succession Wars-level conflict with the focus on military targets and not inflicting mass casualties. Use of nuclear weapons against a planetary target is well outside the scope of what's happened so far.
Added to that, Julian's not the type to engage in that level of retaliation. He sees himself as one of the 'good guys', and while yes, he wants to save his nation and his people, he's not going to do it by engaging in mass civilian casualties for the sake of it. He's fought Malvina Hazen, after all. He doesn't want to become that.
Besides which, if "load up with nukes and jump to the other guy's capitol" was even a remotely viable strategy, then someone would have done it back in the 1st SW.
Unlike the bears, Genocide is not the AFFS' first response