If VV edits, I will.  But otherwise, yes, I'm sure.  

Murtaugh only ever gave into Galbatorix's indoctrination when Thorn's egg hatched.  He said himself that that was his doom, because the love he had for his dragon overwhelmed everything else in him.  His self preservation, his love for his brother, his desire to do the right thing, all of them fell by the wayside in favor of his dragon when he was in danger.  

This is the same.  Z poses a threat to Ashwing when she's most vulnerable, this(in conjunction with Ashwing's own aggression towards her) coaxes Alph into action.  

It doesn't help that Zyloria literally aims the sword for him either. What a strange thing to do.