The risk is not worth the reward.

Please link the scientific based analysis that concluded this for covid. Because even the most basic formal analysis i can think of would result in the opposite conclusion.

You can't prove safety and efficacy in 6 months.

Why not? There is no biological mechanism for serious negative side effects to just appear only 6 months later nor is there historical precedent for vaccines.

Efficacy can be determined as soon as enough people in the trial get infected (that is 100% dependent on the level of infection in the population which is fairly high in the US).

The primary reasons vaccines have historically taken a long time to develop are cost efficiency (not an issue here), lack of infection in the general public (again not an issue here) and regulatory review process (again not an issue, because covid will be prioritized for review. Normally the FDA takes at least 90 days to respond to any application not because it takes that long but because there is so much stuff to review and new applications don't go to the front of the line.)

Plenty of scientist disagree with the idea that you cannot prove efficacy and safety in 6 months and lots of them don't work for vaccine companies or the Trump administration.