I think Mr. Bojangles is a complete red herring. Most likely just a bum, probably a drug addict who'd been rolled, and knifed in the arm. The restaurant was a mile from the crime scene, and there's no telling what direction he came from to get to the restaurant.
He sounds more like the possible victim of a crime on the night in question. Also could have been in a fight or started one, he couldn't finish, but nothing about him is indicative of him committing the 3 child murders. It just plain doesn't fit. He was described as dazed and confused, muddy and bloody. The odds are against anyone who would commit that kind of murder would be dazed and confused by the crime they'd just committed.
People can concoct all kinds of scenarios, but that doesn't mean they're likely. Police look at what they see over and over because what's seen over and over fits, so some scenario pulled from left field is not worth a hill of beans. Take some ridiculous scenario to the police, and you'll be laughed out of the station.
Sure it wasn't a great thing that Ridge lost the Bojangles evidence, but after 1:00PM the following day the entire WMPD was up to their azzes in alligators so it's not hard to imagine that bit of evidence got lost in the shuffle. I don't think malice had anything to do with that loss of evidence. I think they either accidentally lost the evidence or simply discounted the Bojangles incident, and that was that.
Naturally any defense is going to pull up the Bojangles incident and use it to steer things away from the accused on trial. If they didn't, they wouldn't be doing their jobs.