He's not charged with "murder"...he's charged with "aggravated assault" and "felony murder" which, if I understand it correctly, means (felony murder, that is) that a death was caused during the commission of a felony.
It's going to be hard to prove that Travis McMichael was committing a felony when Arbery ran at him.
Felony murder also removes the need for malice on the part of the shooter to convict. That's not going to help McMichael at all.
It's going to be hard to prove that Travis McMichael was committing a felony when Arbery ran at him.
They initiated the incident and McMichael shot Arbery three times. I'm sure the prosecution will be able to prove a felony in that.