Schmidhuber is salty because he believes he invented the ideas behind deep learning and has never gotten the proper credit. So, yes, he wants the Turing award to go to him.
It's not an argument without merit. His work on LSTM and related ideas were really important to the field. And, as with all heroes in science, the deep learning triumvirate of Bengio, Hinton, and LeCunn get most of the credit but were building on lots of existing work from researchers who don't get their due. But, as with all awards, you need to draw the line somewhere.
I understand that, I know he's not a nobody, but why draw the line at him? His own rebuttal shows that he was himself building on previous work and while LSTM are very important, SOTA models are phasing them out in favour of attention based models. In computer vision CNN are still king and as far as I know he has no claim to those.
On top of that (although I understand why a researcher might not consider this to be important), Theano really helped democratize model development and deployment and it was developed at MILA under Yoshua Bengio's. You can't just hand wave the tools that actually sparked the new movement.
It's not an argument without merit. His work on LSTM and related ideas were really important to the field. And, as with all heroes in science, the deep learning triumvirate of Bengio, Hinton, and LeCunn get most of the credit but were building on lots of existing work from researchers who don't get their due. But, as with all awards, you need to draw the line somewhere.