I heard about what was found on the Bitcoin blockchain. I never considered the consequence in this way to be honest. You're right, if it's immutable, then the only alternative would be to take the entire thing down! Including all the steem!! What that would do to the price of Steem and people's holdings.
This could also be an avenue of attack from a hostile actor. I hope they do find a way around this.
I know @dtube has a way around it that can be circumvented, however with steem - I still haven't heard anyone with a plausible solution. Have you heard of what they'll be doing with the bitcoin blockchain and how to hide/take down that kind of content? Price hasn't reflected the dangers so it still standing.