The Blitz change is justified but
Perhaps we can buff the utility of it just a bit? It makes sense that it shouldn't be 30 seconds at rank 1, but now that's it's longer, can that silence duration get adjusted? As it stands 0.5 seconds is barely any room for using the silence portion strategically. The only use it has is interrupting channeled abilities that are already in use. If it's going to be 60 seconds the silence can be bumped to 1 or 1.5 for a bit more decision making into when to use your ultimate.