The point is relative risk, in particular the poster's friends are warning them about Aspartame, while drinking alcohol, which has significantly larger confirmed health risks. If they believe drinking alcohol is safe in the quantities that they do (and given that most health authorities now point out there is no safe level of alcohol to drink), then it's irrational to worry about Aspartame.

The comment doesn't make any point about relative risk. They're only mocking their friend for telling them about something unhealthy when their friend also does unhealthy things. As if it somehow cancels out.

It’s implied.

> I drink diet sodas. I have received many emails/calls/texts from friends and family telling me about the "news" of them being a possible carcinogen. To every such person I say: Alcohol is a KNOWN carcinogen. Drinking alcohol causes cancer. So don't lecture me about drinking diet coke until you have given up on beer

The poster compares the risk of aspartame being a « possible carcinogen » to Alcohol, which is a « KNOWN carcinogen », specifically comparing the different classifications.

But relative risk is irrelevant. They still don't somehow cancel out. My aspartame consumption poses some risk to me, and that risk doesn't depend on the habits of the person telling me about the risks of aspartame.

That’s not the point, there’s no claim it cancels out. The point is about the risk tolerance. We all take risks in our life, and the risks posed by aspartame are lower than that of alcohol.

Calling it whataboutism is disingenuous, they're specifically talking about hypocrisy.