Most tv dubs *are* closed captioned. The problem is that most dub closed captioning (actually most closed captioning to begin with, but especially dubs for some reason) really really sucks, no matter how good the rest of the dub is.
...oddly enough, the company I've noticed that does the best with captioning their dubs is 4Kids, which is all kinds of strange. But it matches the dialogue, it spells names correctly (with how they're spoken), it notes when there's an off-screen noise the viewer needs to know about, and it's NOT SCROLLING which is incredibly hard to read. Most dub captions seem to read like live captions, which are messed up because they're done extremely quickly, even though there *should* be at least several weeks to work on them.
Worst captioning I've ever seen on a dub is on something where I love pretty much everything else about the dub, and that's on Digimon Frontier. When the ultimate warrior Susano'omon appears, they captioned his name as "Suicidalmon", leaving me with my mouth agape and ultimately to bust out laughing, which completely ruined the seriousness of the scene.
...anyway! If I ran Toonami I'd have advertised it rather than doing nothing to promote it and then whining when no one watched it, like CN did.