even ignoring the middle dot, just picking a more suitable corpus for that person isn't necessarily going to make this technique look innocuous - it's still a collection of excerpts taken from what looks like random positions within a document. it looks suspicious.

you could imagine a system which uses entirely normal and habitual tweets, but encodes information in choices of synonyms used in the text, or whether or not punctuation was used in certain places, or the timing of the tweet's publication. lower bitrates, but plausibly deniable as to the message's existence.