That must have taken a lot of valuable time. Which sucks because nobody else would bother to read it.
That is not the issue, the issue is that illegal information could be conveyed that way
Top secret stuff, terrorism ... would that turn the entire blockchain illegal?
It wouldn't turn the entire blockchain illegal.. but it would certainly put you on a watch list.
And I doubt terrorists would reveal their latest plans somewhere where anybody can read it.
An excellent point... to play devil's advocate though, they could send out a notice saying "go now" or something, signalling other jihadis to start an operation they planned earlier.
I think it would be unlikely, but in theory possible. There would likely be other, easier way to send this message however. Shortly after 9/11/11 videos surfaced of Bin Ladin that showed erroneous date/timestamps, it was thought that these timestamps may have included some kind of message so the media self -censored the timestamps to prevent them from being disseminated.