This is a classic situation where your answer will always be wrong...

If you declare an area 'sensitive', they will likely use that as 'evidence' that you are trying to hide something and search that area 'extra special'. If they hurt you in the process, they'll use a 'were not liable' because 'we had to clear the anomoly' along with an 'it didn't happen that way'.

If you attempt to avoid the 'extra special' attention to your 'sensitive' area by not declaring it, they'll claim that you never informed them and that they are not liable for any damage they induce during their patdown. If you complain, they'll likely use that as evidence that you may be attempting to hide something else.

Either way, according to them, they are not liable for any pain and suffering you may experience. And while a civil suit may be warranted, it, unfortunately, would likely be more trouble (time and cost) than it's worth -- something which they are counting on I'm sure....