As long as it's in moderation, it should be fine. Lots of sodium is bad for them, but a handfull to a flock once a day till it's all gone won't hurt them.
Too much salt is bad for birds. But every now and again that's fine.
For some odd reason, there was a weak old slice of pizza and two old garlic cheese bread sticks hidden in our cupboard (I have no idea why they were in there... lol). So I threw em in the coop and the birds loved it. They loved people food, but feed it as a rare treat.