It's no simple thing, it just isn't. It's a complicated can of worms and there's no simple solution or answer. Should people be punished for a tweet they made ten years ago? I don't have a definitive answer for you. Should someone lose their job for a poor decision or a series of poor decisions? Should sins of the past be judged on present societal ideas of what is and isn't okay? You're going to get different answers relating to different scenarios from all sorts of people.
In this case though these are professional coaches working in a very limited pool of jobs associated with what is a global brand, the NHL. These aren't just journeymen and fringe guys speaking up about abuse either, many of these players have had respectable careers and won championships. Some of them were stars. The NHL can't ignore that, and neither can clubs. And they aren't. Calgary was very quick to investigate Peters and handled in in what I thought was a professional manner, they didn't drag him through the mud. Chicago's quickly investigating too and they'll likely take a similar approach. The NHL, the Flames, the Hawks. These are brands and they will protect their interests. And I highly doubt abusing players was socially acceptable ten years ago.
Hockey culture is changing, what's expected from coaches will change in turn. I guarantee coaches at all sorts of levels have been paying attention the last couple weeks.