The OTH discharge is still a non felony offense. He’ll still get some benefits including his SGLI coverage. Unfortunately if he didn’t commit a felony offense he still gets some benefits. I think, correct me if I’m wrong, the Bad Conduct Discharge and Dishonorable are the only ones where you lose all veterans benefits.
I think that SGLI coverage ends when a soldier is discharged/retired. I know that my SGLI coverage ended when I retired 25 years ago.