Yeah, MoR has a much more well-thought-through concept of what it means to be a powerful wizard, and the difference between that and a normal wizard.

And even in canon, I'm not sure it makes sense for them to be surprised he could escape- everyone thinks of Dumbledore as the most powerful wizard alive- but they could have conceivably been expecting him not to attempt to resist arrest, because he's generally more law-abiding than that.