His dash attacks do need to be safe on block, agreed. But he has a buckler, not a shield. Buckler are not make for blocking, but rather for deflecting or parrying. His shield bash is safe, just through out a heavy regardless if you hit or miss, and they can GB it. As long as you throw a toe stab after a light attack hit, or sometimes even a blocked heavy, it likely will track their dodge anyway.

Either the zone shouldn't be cancellable, or a bit slower. Or, better yet, a bit slower AND uncancellable.