The issue of 90 character limit is well known to state and local emergency managers familiar with the Integrated Public Alert and Warning System (IPAWS), but my gut tells me that there were other people issues getting in the way of issuing the warning. An IPAWS message could have been sent saying, "Warning: Fire burning on edge of the city.Tune to radio and TV for information." This is 80 characters long.
It is a totally different situation from this, but I recall being told to be somewhere to brief a legislative committee on an ongoing incident and I had 15 minutes before I had to leave the EOC. I told the operations chief that he had 15 minutes to give me some basic information points on the event. He said, "I can't do that in 15 minutes!" I then showed him it could be done by swinging through the center and talking to 3-4 people and getting a SITREP from each.
90 characters and 15 minutes are not ideal, but it can be done by those motivated to do something in the time allowed.