I think if I met the dude in person I would have a lot to argue with him about, but he's the sort of person that even for the things that we might disagree about, I'm really glad he's out there arguing his case and trying things out.
I personally doubt that you can ever replace the symbolic aspect --- whatever that means --- of, like, 90% of the stuff that goes on in the world that I would call mathematics or computer science, because no matter how "cold" or "meaningless" or "dry" or "purely formal" you happen to feel it is, it's what proofs are made of, and what software's made of. Good mathematicians do "feel" their math, but sometimes you have to understand it on its own terms, and not in terms of concrete, physical analogies. I make the prediction --- and I could be wrong --- that this isn't going to change any time soon. But for the 10% that is only about really seriously quantitative, graphy, numerical things, absolutely it's a great thing to find better visualizations and widgets you can play with, because, for one thing, what's 10% of my experience of math may very well constitute 90% of your experience of math.
And separately, looking past the false dichotomy of symbolic vs. graphical, there's tons of opportunities (even in "my 90%") for the magic ink of computer displays to augment our ability to symbolically abstract and reason about math. Godspeed to anybody working on doing that well.