The way I read it was that they'd tortured Stratton and he had the scars as evidence to prove that they had. They might have been tempted to just quietly execu

The way I read it was that they'd tortured Stratton and he had the scars as evidence to prove that they had. They might have been tempted to just quietly execute him at the end, dump his body to hide that he had been tortured, and then deny that they'd had him (remember he hadn't written home). Instead Hegdahl shined a big diplomatic spotlight on Stratton to try to get them to get them to acknowledge having him alive and deny having murdered him. After that, they'd want to make sure their denial of murder stays true.