The description of the Intellect Devourer in the MM and SRD says
A protection from evil and good spell cast on the body drives the intellect devourer out. … By spending 5 feet of its movement, the intellect devourer can voluntarily leave the body, teleporting to the nearest unoccupied space within 5 feet of it. The body then dies, unless its brain is restored within 1 round.
Is a character functionally dead immediately upon losing a contest of Intelligence vs an Intellect Devourer? [barring a wish spell]. It seems rather draconian for a CR2 creature, if so. [Hell, even if not so, requiring one of those two specific spells seems rough even if one is a 1st level spell, that is assuming it even helps]