They’re about to declare it as possibly cancerous. Not fully cancerous.

What do you mean by this? Everything that can cause cancer is declared "possibly cancerous"; it depends on dose and exposure. Nothing is "fully cancerous" for whatever that might even mean. You can be exposed to radiation and either get cancer or not; it depends on the dose. Would you call radiation "possibly cancerous", or "fully cancerous"?

Analagously, most bacteria can cause infections but they don't always in everyone. So to label a bacteria as purely benign or purely dangerous is just as silly as trying to make a distinction between "possibly cancerous" and "fully cancerous".

Aspartame is in a lot of things, mainly sodas and gum, but you’d have to consume a lot of the stuff beyond a human limit really.

And if someone wants to minimize their risk of cancer, they should be able to make informed decisions. Knowing that at particular food-additive has higher-than-baseline chances of causing cancer allows someone with a different risk-aversion profile to make decisions wisely. If you don't mind the incidence rate at the dose you consume it at, that's fine as well. But it is useful to have it be public knowledge if something is potentially cancer-causing.