Not the direction I'd like to see us going, but I wonder if brain activity is the same thinking a thought and intentionally uttering it. They have only been able to decode phrases from the activity while a person is actively talking and translate it into the words that were spoken. Who knows how brain activity might differ when it's pure thought. Considering the limits of language and how quickly thought happens versus speech, reading thoughts might be like deciphering short hand or another language entirely from what is happening at the moment of speech, when the brain is translating it to language. Being able to say "this is what a brain looks like when it intentionally utters a phrase" may not translate to how the activity looks when the thought in considered internally.