That would be me!

I use 30cm (12 inch) Addi's for socks and mittens (one, not the two needle method popular right now) And technically Addi and INOX are plastic because they are nickel or gold plating on a plastic base. (I would avoid the gold ones) Addi also makes bamboo ones I believe, like the ones you showed above.

A 30cm needle doesn't look anything like a knitting needle when it is part of the sock or mitten, so usually doesn't get a second look. But LH still has a confusing/contradictory rule and some FAs think it is banned altogether on LH, so I generally don't knit on my LH flights.