I'm assuming he is at least 50% disabled? From what I gathered if you are 49% or less with combat operation verification and separated short of 20yrs, you have pretty much bumper to bumper coverage up to the 5th year anniversary of your separation date.
Afterwards, you are only covered by the VA for documented conditions directly due to service. Any insurance coverage then has to be obtained traditionally.
I did not do 20 and my documented conditions were downgraded in severity resulting in me not meeting the 50% threshold of tri-care even with copay. Like any quality government system, it ended immediately once I was administratively downgraded.
I didn't like dealing with the VA bs before this but now I am completely done with them altogether. That single payer system is trash. Pray we don't go entirely socialized medicine any time soon.