Veni. Vidi. Vici.
-Gaius Julius Caesar
The Only Thing to Fear is Fear Itself.
-Franklin Delano Roosevelt
And with the 9 year old girl on the victim list, he was indiscriminate about who he was going to kill.
Before you criticize someone you should walk a mile in their shoes, that way when you do criticize them you'll be a mile away and you'll have their shoes.
It's an assassination in that he attempted to kill a public figure. It's a nut who was probably working alone or with only one or two people and is pretty clearly mentally deranged. The two are not mutually exclusive.
This qualifies. You don't have to be a professional to assassinate some one. This is however just a semantics game. It's murder and attempted murder either way and I think both you and I hope he never sees a day of freedom again at the very least.