From my understanding quoting a single tweet, due to its length, wouldn't constitute a violation. However if you copied anyones twitter log, then yes that would

From my understanding quoting a single tweet, due to its length, wouldn't constitute a violation. However if you copied anyones twitter log, then yes that would be a gross violation of copyright. The whole is worth more than the sum of its parts, which is frequently how copyright law views the use of small pieces. I can legally use someone else's artwork in a collage or in my own non-derivative work (although derivatives basically don't exist in artwork, but for the sake of argument they do as they are still legally recognized) and I am at no legal risk because my collage of 1,000 pieces of artwork creates a whole new piece of art in itself. The book in question is likely a lazy assed crowdsource, likely much of which was written by average Joe's. However the real question here regardless of country is did the author make something new in their book? I remember reading a correspondence book that mixed multiple anonymous letters together to create a chapter, but no two were destined for the same person and it completely cleared any question of copyright infringement, however I doubt this book of tweets was artfully crafted together to evade copyright on the merits of its own work. From what I read of it, its simply hoping to avoid copyright on the duration of material, which it is likely going to do but legally speaking it shouldn't if it really is a lazy crowdsource compilation.