UFC personnel made a bunch of bad mistakes (keeping the cameras on him whilst having the seizure, making him stand, walking him out, etc) … they were lucky in the end he was ok, if he got a brain bleed or went into a coma they would have been Fd with those “protocols”.
Having said that, as scary as flash KOs are (especially with rigidity and/or seizures) according to most research they are way less damaging than lots of sub concussive blows; most serious events (brain bleeds, coma, death) happen after prolonged beatings with repeated knockdowns, almost never after one complete sudden shutdown.
So physiologically he might actually be fine and with no consequences at all; the question is can he recover psychologically in terms of confidence and risk-taking, especially after he’ll watch the replay…
I got KOd once and immediately quit all fighting activities … and still feel somewhat uneasy about the experience now after 25 years. But I’m not a savage like the pros.