Ah, the worm in the Tequila bottle. Let’s start here: it isn’t a worm at all! It is a moth larvae called a gusano de maguey. And if you find one in your bottle of Tequila, do not drink, we repeat, do not drink that Tequila.
While the CRT allows for other additives to be in Tequila, a larvae is not one of them.
Now if we are talking mezcal vs Tequila, that is a different story! The “worm in the bottle” schtick really began in the mezcal world, perhaps as a marketing ploy, or a way for brands to show the “strength” of their product(if the larvae stayed whole, without decay, it was an exemplary product).