I have flown with a bike several times. Each time TSA simply looked inside the box without removing the bike. I was permitted to be there during the inspection. After the inspection the TSA agent tapped the box back up, under my direction. They have always been very helpful and cooperative.
Italy was the strangest of all. They took a quick peak inside the box,, they then put it back in my possession and I was instructed to take it to the loading area (not accompanied by anyone).