Given that the Order assists Corsairs, they are a fair game for the Zoners. If the Order wouldn't like to get shot, they wouldn't be involved in this conflict in the first place.
As for the Core teaming up with the Outcasts - players will always do player things. Order assisting Corsairs is the same nonsense given that the Xeno Relics are alive and dangerous artifacts, and Corsairs are happily selling them on the blackmarket, basically spreading dangerous alien tech among Sirius civilian population.
That's not really a problem for the Order to be honest, We don't shoot upon zoners unless shot at first for obvious reasons, but what is a joke is the Core assisting Outcasts when they already have the help from 99% of the Indie Zoners and Factions of the zoners, It even states in the event description that Core are to engage both sides *bla bla bla*