On the contrary, he is definitely responsible. First, because he was the head of design, and keyboards are part of the overall design. Second, because he pushed for or accepted the push towards ever thinner and lighter products, at the expense of almost everything else. And third, because of the push towards more uniform/beautiful/symmetric designs at the expense of functionality (limited ports, USB-C only, cursor keys on the keyboard).
He is very much responsible and I think what we saw from Apple in the last few years in the Mac lineup was below expectations. I've been saying for some time that it seemed like Jony Ive was running rampant within the company, not using or loving Macs himself, but deciding about their design, with no one in a position to say "No" (like Steve Jobs did).