I see a problem with this edit as it stands now. Since the Republic still stands after the Resistance learns of the Starkiller and its capabilities, there should be some scene where the Resistance warns the Republic, or at least makes some mention of their danger. Otherwise, it seems like the Resistance is extremely negligent in their duties and allows for this atrocity to unfold at such an epic scale. At the very least, if the Republic thought that it was in danger, they would have evacuated the government to a secret location.

There may be a way to easily fix this, however. During the Resistance briefing scene, simply re-insert the line from Leia that ‘our system is the target’ (eliminate ‘next’, obviously). This way, the Republic will assume that the First Order means only to destroy Leia and the Resistance, a group that the Republic dislikes anyway. Then we could record a line that is said by someone in the crowd to the effect of ‘The Republic won’t help us!’, and then re-insert C-3PO’s line: ‘Without the Republic fleet, we’re done for!’.