I've said all these things before, but the first and most obvious explanation for at least part of the delay is they wanted to see what they could accomplish in terms of signing free agent WR's before making the firm decision to move on from Dez. I don't at all think they would have been comfortable had they been left with essentially the same group of receivers as last year, minus Dez. Replacing Butler with Thompson certainly wasn't enough.
Admittedly that may only explain about 2 - 2 1/2 weeks of the 5 week delay though, but that brings me to the possibility that was partially set out in the post you just quoted. Hurns clearly wasn't their first or only target, and he wasn't a high dollar signing, so the team may have still been weighing its options to sign another free agent, or even to keep Dez in addition to Hurns, and thefefore they may have chosen to let free agency play out longer before making a final decision. I wouldn't necessarily say that's a suspicion of mine, but I think it's a reasonable possibility.
The other thing I mentioned a few posts ago is that they probably were trying to trade Dez, and wanted to give it as much of a chance as possible to materialize. There certainly were reports that they did try to trade Dez. Realistically, why wouldn't they have given that as much of a chance as possible to happen?
I certainly think all of these things are more reasonable possibilities than that the team was just doing it out of spite.