Everyone should be due EC261 if there was an 8 hour delay. This is an operational issue, the airline is supposed to manage the payload to be under the maximum allowable take off weight. There are standard calculations and tables for this, I expect Florence has a shortish runway and there are considerations for atmospheric pressure and temperature at runway level.

The solution seems reasonable to be honest in that everyone got home, but if 50 passengers were affected, it seems this wasn't just a marginal issue. A more sensible method might have been to offload bags and send the later, but hey ho. There was probably a reason for doing this.