The word "all" as a modifier to 600k is not in the text;
see for eg:
And here is the problem framed in terms of gains:
If you choose Medicine A, 200,000 people will be saved. If you choose Medicine B, there is a 33.3% chance that 600,000 people will be saved and a 66.6% chance that no one will be saved.
Which medicine do you choose?
Although the number of certain deaths is the same in both versions of the problem, people take the safer option
The lack of scale prevents an analysis of proportionality.
For example:
600k out of 500,000,000?
or
600k out of 1,000,000 or 1,000,000,000?
Given the downsides are equal, the omission begs the qeustion about the rate of success. The rate of success is not a trivial source of people's bias, because empirically "non-success" is often accompanied by adverse effects (a/k/a side effects) as well as additional cost. The result is a leading question. In other words, the language is manipulative.
But do we really need this study to tell us this? C'mon, that is stupid. And has nothing to do with Mandela.