I don't think it's sexual assault at all. I've just come back from America and firstly, you only get the pat down if you refuse the full body scanner, which I don't see why you would as the scans are examined in private and nobody can possibly see the pictures except for the security officers. The people operating the machines don't actually see a thing.
If you did opt for a pat down, surely you are going to expect them to be thorough? You're not just going to think "oh I don't want to go through the scanner, therefore nobody's going to check what's hidden in my bra"
Also, the checks are performed by a same sex member of security and it is also possible to ask for someone such as a family member to be present.
This woman is just begging for attention.