There's absolutely no reason to check a lanyard. Granted there's a lot of metal on it and it may get hand inspected but it isn't dangerous to anyone. The little pins in the back are no different than the pins on pilot's wings, military uniforms, etc.
Everytime I have flown with my pin bags and my pin lanyard I have never had any problems packing them in my carryon bag. Sometimes when going through security they get searched and sometimes they have not, so there is always a 50/50 chance of that happening.
In August I take 5 or 6 pin bags to Disney. I won't check them as I have heard horror stories, so I carry them on. Sometimes they bag check and sometimes they don't. Not a problem. Penny