Who said anything about governments dictating your feelings?
You did.
Despite trying to backpedal, your original suggestion, which is still there is:
You would "certainly back a hefty fine", based on the government "making up ways to fine people", for those people "NOT denouncing and discouraging mass shootings".
So you're explicitly saying you want people fined unless they publicly denounce mass shootings.
That's the government dictating the feelings that you should have and punishing people if they don't feel that way, or even if they do feel that way and don't say so publicly.
You assume this would be used on Pewdiepie to start with, but unless it was made retrospective (which is illegal under international law), it absolutely wouldn't. I can tell you who it
would be used against - it'd be used against Muslim clerics and community leaders who didn't immediately and comprehensively denounce some act of Islamist terror. It'd be used against left-wing activists for not apologising for events in some far-off purportedly-left-wing country. It'd be used against minorities standing up for their rights - forcing them into public statements whenever a single one of them stepped slightly out of line from the government's perspective. It'd be used against striking workers, or against immigrants.
That's the inevitable result of what you want.
How did you even get from "fine a guy with massive amounts of influence if he doesn't openly discourage his fanbase from murdering people" to that?
How do
you not?
The first thing you need to consider about any law is the full set of use cases where it might be applied. Not doing that results in the kind of bad law that you've suggested.
Between these absurd conclusions from, I assume, a hypothetical extreme of an abuse of a power given specifically to combat online brainwashing and not offering any solutions of your own besides "we can think of something later", I'm not sure you're taking this very seriously.
This is almost as bad as your post patronisingly telling me people had died.
I don't agree with your idea, because I think it's a stupid idea. That doesn't mean I'm not taking this seriously. I am allowed to think your idea is stupid.
This rush to do something dramatic just to be seen to be doing or saying
something is how we ended up with the aftermath of 9/11 when the US embarked on a sequence of truly idiotic military actions because the people in power had to be seen to be acting. Make it big, make it seem purposeful, don't worry about the details, just do
something - and you're doing the same thing. New laws written as an angry reaction will not fix things.