Probably if Mary-Sue from Idaho, a shop clerk tweets this it’s not exactly the same if a former diplomat with international connections and public influence does it?
You're grossly overselling his influence. He doesn't have the ear of the powerful or the mob. Even if he were to explicitly call his followers to take up arms - which is a long way past the quoted statement - I very much doubt any of them would.
If they think that then why just him and not the thousands of other people tweeting similar things?
The thought process is evidently "oh, it's that bloody git again, have we got anything we can pin him for this time?"; if you don't see that it's you who's being naive. (I'm agnostic about whether it's specifically about Scottish independence, the Assange case, or something else; one way or another he's a thorn in the side of the powerful, and that's why the book is being thrown at him)