I think they were just going to remain quiet. The Lakers aren't working him out. They aren't going to pick him without one, so it's not for that reason. Maybe they want to make Dunn seem like the #3 prospect out there, to continue to press Philly for a trade. Maybe they like him and are keeping it quiet to potentially trade down and still get him, although he's worked out with Phoenix and Minny already, so I can't see that being a viable stance.
In other words, saying nice things probably isn't going to help much. And it's impolite to say mean things. The Lakers aren't going to pick him. The Suns might, but they're going to do that regardless of what is said. It's tough to see another team loving him so much more than Dunn that they'd want to trade for him. I guess there's some value in trying to move the Suns to trade up a spot, but that only works if they really love him. So it's probably best to just keep quiet.