That website is wrong, with double strength, you should be using 4-5 ml per 100 l of milk diluted 1:80 with distilled water. Meaning, even less than 1/8 tsp per gallon. I wish the whole tsp system would go away when measuring rennet, esp with double strength.
Yes, you can save the cheese. It's good that you used floc, otherwise, you would have gotten an ultra moist cheese that would very quickly turn bitter. Follow through with the recipe as usual, but increase your brine time by 10-15%, about 4.2 hrs total, using no more than a 20% brine (do not use saturated), and decrease the aging temp to 50-52. It will take an extra 1-2 months to age. The higher salt and lower temp will help equalize out the peptidolysis.
edit: 22% and 4+ hours is a it much. An 18-20% at 4 hrs would be better. You want to get the salt to the middle as quickly as possible, and at a good concentration, somewhere around 2%