The language is unfortunately imprecise (or rather too precise) but I’d imagine this is simply allowing security staff discretion to refuse suspicious circuit board looking devices. They’re not going to be checking for brand names.
Yeah, exposed circuit boards are things most people only see in three settings: (1) when one of their devices are broken, (2) bomb in a movie, or (3) it's the 00s.
I think they're more concerned with preventing a panic over any of the concerns about what someone can do with a Raspberry Pi.
Yeah, I'm not really sure how this became news. It's not weird at all for event security to have a discretionary rule for if you don't know what it is and its purpose isn't obvious then feel free to not allow it.
This just seems to be that but phrased weirdly.
They would not allow suspicious looking PCB's in regardless. If that's what you wanted to communicate, you would just add something like "suspicious electronic device" to the list. It's still a legitimate question as to why these two brand names were specifically added to the list.