Guess what? Bullets are still faster. By a lot. So much so that Harry's reaction time is pathetic in comparison. That's the reason the whole 'Muggle with a gun' thing happened. Because, regardless of what Rowling has or hasn't said, it's true. Bullets move so fast that by the time you could flick your wrist, you've already been shot. The human body cannot keep up with bullets. And Harry Potter has never done anything that suggests he is an exception to that.
Against one singular opponent who had the exact weirdness to allow Harry to live. If anyone else had cast the Killing Curse at him, he would've died. Had Voldemort used any other lethal spell, he would've died. Or a knife. Or his snake. The point is, the ability to survive what is actually a really mediocre instant kill spell, from a highly specific individual, in highly specific circumstances, hardly points to his ability to survive being frozen inside out.
He also sucks at it. Really really badly. It's a canonical weakness of his, and Dresden has actually been extensively trained in it, both on the offense and defense. To the point where he could literally eject Harry's soul from his body and wear his flesh like a suit.
Nah, Dresden could just focus all the gravity from a couple hundred meters to Harry's skull and watch him go splat. Or you know, just shoot him. He has a gun, and is a pretty good shot. And if he really needs to, it would be pretty trival for him to steal a sniper rifle or the like.
It's a maybe in the sense that I'm only familiar with Constantine through that one movie of his.![]()