That looks very interesting. Instead of the blacklist you should offer a minimum price for sending messages. Annoying users with an urge to communicate would simply pay the recipients for getting their messages/insults. I'd find that fair :-)
Regarding the update interval: Is it only possible to send a message every 60 seconds? I thought the duration is 20 seconds for posting content, or does that only apply for comments?
If the time limit was zero and you combine the chat function with DLive, you'd get yourself a nice live cam business. Not the kind of thing I would engage in, but surely a very profitable business. After all, users could pay their cam girl by simply sending a message while the girls (or also guys?) could charge a minimum price for their attention.
I would upvote you now, but my one Cent won't make much of a difference to the 775+$ you already got for the post :-)