I see nothing unique in your situation that has not been covered in the sticky
1. The more times he goes to the well, and more he drinks each time, the more likely the well will go dry
2. He has weak ties to the UK
3. If asked to withdraw his application to enter the U.S., he should not attempt to enter for some time. If he is given an expedited removal, it is a 5 year ban. Between the two extremes, his ESTA could be canceled. Using a pre-clearance port will avoid expedited removal.