one of the ladies in my knitting group works for the TSA at the local airport as a bag screener
she told me that scissors are now allowed (but must be blunt tipped), knitting needles of all types are allowed if there is a project on them (empty needles must be checked). you can have aluminum but bamboo or plastic are less apt to cause issues with those TSA employees who are anal retentive. and putting point protectors on your needles will help speed things along.
that's what she told me!
I asked my husband about this, since he works at a checkpoint and in baggage for TSA, and he said rest assured the rules do not say this! That's an old rule from several years ago and they have since changed for carry-on. Also, the rules for bag screeners are different than carry-on screeners. You do not need to have a project on the needles, nor do you need point protectors. He did say she's right about anal TSA workers.
Just smile and nod and explain whatever you have to, but in their operations rulebook or whatever it's called (Top Secret Government Stuff or something) knitting needles of any type are allowed, along with sewing/embroidery needles, and scissors with a 4" blade or smaller. The TSA website is fairly up-to-date and you can always check with the airport itself before packing up and flying out.