So, not really a big spoiler in any sense, but, regardless:
!After one fairly extreme injury to come, it is explained that Viltrumite brains can survive for a decent period of time without oxygen. With the absurdity of their healing capacity, it stands to reason general trauma counts as “heal-able” for Viltrumite brains.!<
At this point, he should be a deranged viltrumite with that head injury.
So, not really a big spoiler in any sense, but, regardless:
All this to say, brain must go squeesh.