It is absurd, but I think it's also common sense. I think it's a good assumption that airport security is not going to be that technically knowledgeable.
I wouldn't touch the topic of Bitcoin with a 10 foot pole around strangers, let alone people with the authority to deport me. I still can't explain it to my friends in a way without making it sound suspicious.
This is pretty much true of clearing customs in any other country. The reason we hear so much about the US is because it's a really big country.
(As an American, I hate crossing the UK border just as much as crossing the US border. What's the point of being in the EU if you aren't going to act like it? :)
But that's pretty much only because of the UK. There are a few countries that are supposed to be in the schengen area but aren't, a few countries that got in because it would have been impractical to keep them out, and the EU countries except the UK and Ireland (who are only out because of the UK).
What is absurd is that whether you can enter or not isn't down to any rule - it's down to the particular low paid moron on the particular desk.
I've been told my visa wasn't valid because there should be a blue copy instead of a red copy (he was wrong - as the INS eventually told me) I have been told that I'm only allowed so many visa waiver visits (wrong), that I can't visit my companies US office under visa waiver (wrong)
It's as if every time an airbus landed at a US airport it was upto the baggage handler to decide if it met FAA requirements
I wouldn't touch the topic of Bitcoin with a 10 foot pole around strangers, let alone people with the authority to deport me. I still can't explain it to my friends in a way without making it sound suspicious.