Yeah, the way Raise Dead works in D&D is you literally are dead, your soul is in the afterlife, you know who is raising you and can choose to come back or not.
But...we're dealing with Revivify, which has a time limit of 1 minute and is a 3rd level spell instead of a 5th level spell with a time limit of 10 days.
The idea being that the tadpole can wait out the 'minute' or so of story time. You'd need Raise Dead and let them be proper dead for a day. Of course, Raise Dead requires an in-tact body and the worm could destroy the head as a final act of vengeance. Then you'd need Resurrection, a 7th level spell.
