They can though.
If you get knocked out youre in a coma technically. Coma doesn't always mean your hooked up to life support fighting for your life. Boxers go to the hospital after almost every fight and normally have similar type injuries and theyre home that night.
He was probably in and out for a couple hours. Once he was stabalized and regained full consciousness they patched him up and sent him home. The fracture was probably very minor so once The bleeding stopped there really isnt much else they need to do, just go home and rest. Im assuming thats how it went down since well.... they say hes at home already.