Chris  as I mentioned every talk's participant can see that someone corrected/edited a message (username and time) and this person who edited the message will be under suspicion and content of the message. This ability maybe useful in case if someone in your talk write bad content and you don't want to delete the whole message, but you may edit it and remove only some part of it. 

BTW: You can edit html code of the page without any special rights, you just need to open developer tool and edit and then make screenshot for police.

Anyway, we will add ability to disable edit option for talks' owners or connect it with membership levels.