Deleted messages idea
Have messages that been purged by moderators so on the caster side, they see it as <message deleted> or blacked out instead of the strikethrough. Make it so that the caster has a choice to look at it or not to see what has been deleted under their own discretion if it's a spoiler or something malicious.
Scorpio SW commented
I was going to suggest something like this as well. It would be nice to be able to fully delete a message without the strikethrough in some instances, such as spoilers (the streamer can still see it with strikethrough)