Hi, welcome to BYC!
I returned home yesterday to 2 out 3 bloody boys also.
The swollen eyes will very likely subside on their own just as they do for boxers and the like. I would think as long as he can make it to food and water then he should be fine...
Personally I might butcher him too.
But since you don't describe him as unwanted... I would pay attention if he is eating and drinking or not. You can either let him be or provide some support with electrolytes, vitamins, and probiotics. Maybe provide some nutritious snack like scrambled eggs. Assuming he can still avoid predation..
Has he mingled back into the rest of your flock yet?
For my previous boys... it was swelling of black eyes that kept them mostly closed and not dried on blood. I personally won't tend minor wounds, seems to me like them bleeding out helps push nasty stuff out of the wound... but I learn something new ALL the time.
Hope he recovers quickly!
Are they staying free range while you are gone?