Praedyth was a Warlock. Which I can actually understand why. Warlocks are known for their intelligence and vast knowledge. I could be wrong, but this is just speculation, I think Praedyth likely went with Kabr to understand more about the Vault of Glass and the Vex. Perhaps he did it for his own reasons, or for the Warlock order or maybe for he Future War Cult who knows. And if you find the dead Ghosts on the Paradox mission while it's thebdaily heroric, he uses words and phrases that sound like a scientist or a historian type of person. Warlocks like to understand things and that is how I think Praedyth was a Warlock.