Trigs will not shoot you, but EDENCOM will now, if you get ANY negative standings with them.
EDENCOM holds major amount of invaded systems already, so you may want to support that side more than trigs.
Here is how to get GOOD standings with EDENCOM again, so they dont shoot you:
Join one of player made EDENCOM defence fleets in a high sec system near you, and shoot trigs together. That will make your standings with EDENCOM npcs go up and you will be protected in high sec minor victory systems and fortresses by roaming EDENCOM fleets. The trigs also drop nice loot, and you get payout from destroying them, while protecting yourself and systems you like to fly in, also GUNSTARS will not shoot you.
EDIT: apparently its still possible to get neutrality towards both.