This is tedious.
The terminal in closed. If people arrive and the terminal is closed then ask them to point to the clause in the T&Cs of their tickets which says that they have 24hr access to the terminal.
Their ticket clearly states that check in opens 2 hours before departure, if they decide to arrive 8 hours early, then that is their risk.
Now, we are talking about a handful of passengers that had a bad experience, so what? In % terms it's minimal!