It isn't the responsibility of Staff to explain rules that are publicly made available both on forums as well as at the beginning of each round. If a player chooses to ignore reading the rules of which a lot of time was put into, they are liable for whatever slip-ups they do.
That said, Staff should also help out whenever given the chance as their job is to better the Servers and maintain order. It isn't much to just say "If first reaction is said, the red who does it first dies. If last reaction is said, the last person to do it dies." All in all, not much can be done in terms of punishment in this particular case. Maybe a reminder to the Staff that they should try to help out others, even if the questions are sometimes frivolous.