The day NSW or any US Military force is kicking in the doors of US citizens will be ....very very bad. I hope that never happens.
I believe the only driving force behind this was NSW's manning issues.
Flash,
Students from foreign armed forces do attend BUD/S. They are granted some extraordinary benefit of the doubt on some evolutions. i.e. wetsuits in Hellweek and they never seem to fail anything no matter how poorly the perform. But, the only foreign officer in my class was absolutely hard as nails. He was Thai Special Forces and kicked ass.
My class had four officers from the US Air Force Academy. I dont know the details of how they came to BUD/S but I understand they were stellar performers in school. One graduated, his name was Doolittle (I shit you not) and the other three did not. My boatcrew leader in Hellweek was one of them, Defazio, a great guy and I was sorry he didnt stick around.
We had a former USMC officer turned LTJG. Again, I dont know what process he went through to leave the USMC.
I wish I could offer a better answer Sir, but thats all I can recall about classmates from other branches.