2nd degree would have been a lock.
Angela Corey must deliberately overcharge to assure acquittal and the accompanying outrage from the low-information types.
Methinks you do not understand the necessary 'intent' element of first degree murder.
It doesn't matter a whit what Dunn intended when he went to the convenience store.
It matters only whether Dunn had formed the requisite intent before he reached across the console, opened the glove compartment, removed his handgun, chambered a round, and began shooting. Crim. Law 101.
I agree with you that second degree murder should have been a lock.