I raise my hands on Xcelerator all the time. I just raise them right as the ride begins to launch. If you sit there with your hands up before the launch, the ride ops will act all psycho like you're going to die. if you don't lower them with the 4 ride attendents and ride op shouting to keep your hands on the grab bar for your own safety, they will abort the launch. I've only seen 1 person disobey the ride ops' instructions, and it was a ride op on her day off. It was more of a joke though. the ride op could care less if she sees a few hands come up during the launch or top hat. its not like she's going to call security.
i wonder if the TTD ride attendents are going to strap you in personally like they do on xcelerator. all you have to do is plop into the seat, and they'll come collect all loose articles, fasten seatbelts, TIGHTEN seatbelts (and I mean as much as possible), and staple you. some of the ride ops don't care if you lower the lap bars (heck, the safety signs say to), but other will get mad.