There is no topic in which you'll get 100% of people to agree with you, and this is no different. There will always be people who choose blue. Arguing that you could ever get 100% of people to pick red is a coping mechanism to deal with the knowledge that your choice to pick red will result in some deaths (i.e., unless blue wins).

That isn't to say I categorically judge anyone who would choose red.

If there's good reason to believe a majority and especially a supermajority would choose red over blue, then choosing red is indeed the only rational choice, and convincing overs to do the same is the only way to save lives.

What I like about the question is that it can be used to measure whether a society is low trust (majority red) or high trust (majority blue).

However, where I take issue with the article is the assertion that it's impossible to get a blue majority, especially in the face of polling that suggests such a majority already exists. The article's claim that choosing red is the only moral choice seems at best to be self-delusion.

The utility of choosing red and the morality of convincing others to follow suit maximizes the larger the currently expected pool of red gets, sure. However, while choosing blue has less and less personal downside the greater the expected majority of blue there is, similar to red, the morality of choosing blue maximizes the closer you get to an even split, since it's the product of the potential lives saved by going blue and the likelihood your individual vote will push it over the edge.

Personally, I'd choose blue. I'd rather sacrifice myself than be party to the deaths of billions of people, so if there's even some hope at convincing the majority to go blue, I'd feel obligated to stay with it even if pre-polling suggests things initially tip toward red. I'd also be a bit wary of living in a society now devoid of anyone willing to self-sacrifice. I'm not convinced most people choosing red give that any thought.