This guy should be considered a US citizen by birth, not a natural born citizen, but simply a citizen as transmitted from his US citizen mother. I think that’s as it should be, and if all the necessary facts can be established, he should be recognized as a citizen.
Sounds like he’s enduring a lot of problems as a result of the proper paperwork not being filed timely. And he might bear some of the blame. Just not enough facts known.
Boo hoo hoo. What you think should be is not what the law is.
This is not a paperwork issue. He does not meet the criteria for being a US citizen. He is a U.K. subject only. He should try to straighten his life out over there.
Not all US citizen mothers can transmit citizenship. There are other conditions that must be met beyond the genetic or gestational connection.