I'm gonna play Devil's Advocate here: This is an awful decision. Now we have TWO place holders for long-running shows at the start of the block, and they're not going to leave anytime soon. Just when Bleach is going into reruns, they make the schedule worse by putting in MORE reruns and pushing the premieres later into the night. That doesn't make things better; that's poking us with a stick.
Here's an idea: Why not air THIS at 5AM instead of the overplayed InuYasha? When this show aired on CN's Toonami, they at least had the decency to air double premieres because they were aware of the show's length. This is gonna be brutal at one episode a week.
Considering how they had to buy the rights to air Naruto again and it was a pretty big hit, I don't think that it would have made sense to put it at the 5AM slot, especially when Bleach is going into reruns. If they go into the filler arcs, which might be possible given what macattack already mentioned, then it won't take as long to go through the series and by the time they get to that point, they should be able to get Shippuden. It's also possible that they could get the 11PM hour if the ratings continues to improve and airing uncut Naruto would give them a pretty good chance for something like that to happen. Plus, if the block continues to improve ratings wise, they could get more of a budget to afford more and better shows on the lineup, which is one reason why I think putting Naruto on the block is a good choice. Putting Naruto right after Bleach could also help them to make Shippuden the series to replace Bleach once it finishes up in 2014. Having a fairly popular Shonen series would really help Toonami and establishing Naruto now will help it develop an audience so that Bleach ending in a couple of years won't significantly hurt the block.
I'm still not sure if I'll watch Naruto. I just have the TV on during Bleach to see the promos since I don't care to try and figure out what's going on in that series, but I don't know if I'll do that with Naruto just yet.