Wasn't the whole point here that the messages wouldn't get reordered? There would be one definite order that everyone would see. Again, if the message isn't timestamped by the sever, it would need to appear visually differently, so that everyone knows about this. And nobody says the server has to accept messages with arbitrarily delays either.
My point is that some limited reordering maybe should be allowed, but not too much. That is to say, the problem isn't as simple as just doing it one way or another way. Every approach has some disadvantages.
I know you were trying to reach that conclusion, but my point was that the design I suggested neither seemed to have the problem you suggested, nor is reordering a necessary outcome, from what I can tell.
