It is indeed specifically illegal to marry your brother, and it was also in the furtherance of immigration fraud.
A. It is specifically illegal to marry ones brother, and,
B. is even more egregious since Omar’s illegal actions
were taken in the furtherance of immigration fraud.
Nails it.
Immigration fraud can result in fines, imprisonment, and deportation from the US.
The penalties depend on the type of fraud and the circumstances of the case.