Are you just being argumentative for the sake of it? There is a world of difference between Quade's indiscretion and what David did in terms of impact on team culture.
There is only one measure on what sort of impact David's behaviour might have on the team's culture and that is how it affects what the other players think of him. Given that he hasn't been a Wallaby for some time and the previously apparent high esteem the players held him in, I would be shocked if this has had any negative impact on team culture. I wouldn't mind betting that it might have even had a positive impact.
I think Inside Shoulder's point is more along the lines of it not being the impact of the specific action on the rest of the team but the action itself not being core to a good team culture.
Everyone lauds Pocock because he stands by his beliefs and most of the causes he fights for have fairly widespread public support.
What happens if one of the fairly devout Christians in the team decided that they wanted to leverage their public persona to campaign against their perceived ills of abortion and homosexuality? Far less people would be arguing that was good for team culture.
As many fans have pleaded for a long time, they'd prefer all the media attention to be about the rugby, not about off field issues. If it's accepted that players can act in ways that are considered 'bigger than the team', you'll invariably end up with some of those actions hurting the team culture.