I see his conclusion is deep learning doesnt work here - but it might be interesting to incorporate word2vec features into this and see if the performance doesnt increase (or at least hover around 94%)
This is pretty straightforward to implement in keras, you just need to supply pre-trained word-vectors weights to your embedding layer.
Embedding(vocab_size, 300, weights = [word2vec_weights])
Where 'word2vec_weights' is a numpy matrix with shape (vocab_size, 300).