Cranberry Wit question

I think I got this from the BYO website...
Carissa Sweigart's Cranberry Wit
5 gallons/19 L, all-grain; OG= 1.046 FG= 1.011; IBU= 22 ABV= 4.4
 
Ingredients:
• 4.5 lbs. (2 kg) of flaked wheat
• 5 lbs. (2.3 kg) of Belgian Pilsner malt
• 1 oz. (28 g) Sterling hops
• 1 oz. (28 g) Golding hops
• 0.25 oz. (7.1 g) bitter orange
• 0.5 Tb. cinnamon
• 1 tsp. coriander
• 0.35 oz. (1 g) grains of paradise
• 0.66 gallons (2.5 L) Ocean Spray cranberry juice
• Wyeast 3944 (Belgian Witbier) yeast
• Wyeast 3463 (Forbidden Fruit) yeast

at the end it says to add the cranberry juice to secondary and 2 Tbsp each of "potassium sorbate and potassium metabisulfite (for stabilization)". Then bottle and age 3-4 weeks.

My question is... don't those chemicals stop or delay fermentation? And if so, how do the bottles carbonate? (I don't have a keg set up yet.)

Recipe is here:

http://byo.com/wheat-beer/item/1958-carissa-sweigart’s-cranberry-wit

K-meta and sorbate will kill the yeast and any other yeast you put in there. I would not follow these part of the instructions. I bet the recipe creator kegs and did that to end up with a slightly less dry beer.

If you're going to do this, and you're bottling, let the yeast eat up the additional sugar before bottling.