I think Shane is becoming a Rorschach test - and by that, I mean the character from the Watchmen. If you read Watchmen and think Rorschach is the hero, you might be inclined to think Shane is in any sense admirable. In fact, Rorschach at least has ethics and not simply principles: Shane is all about his survival and, to a lesser extent, the survival of his personal group. Rick thinks about the bigger picture, the possibility of a bigger group whose needs might all be met. That's not vacillation. That's leadership.
Anyone who thinks Shane is anyway a leader or a hero needs their brain checking, he is a horrible evil person + a giant ticking time bomb.