You use a (heavily questioned) statement of an organization as a base for your claims when the organization explicitly doesn’t support your conclusion. It’s a fact that WHO still claims there is no dangers consuming the recommended daily amount.
The method used on rats to estimate the dangers is the method used when estimating dangers every other substances. So the argument is valid as long as you claim that every other substance cause cancer.
Then you end up nibbling on edges of the classic “the great aspartame conspiracy” but what you totally miss that “big sugar” is even more powerfull…