Part of the use case of a "trial by fire" approach is that the idea is to come up with a better approach than any one of us could ideally. One isn't interested in trying to use their idea as-is, nor in simply disregarding it, but in probing, understanding, and adapting it to the case at hand.
That means arguing about it in detail. Explaining from scratch may be a necessary prelude but it doesn't help really with the final deliberative process. The key is to ensure that everyone knows that these are good-natured and that most people will shape the outcome even if their ideas are not adopted wholesale.
The goal is to have an argument where everyone collectively wins, and where each reasonable participant (meaning, most of the time, every individual participant) individually wins as well, in the sense of having their concerns incorporated into the final view.
You know, explaining an idea to somebody, from scratch, it's the better way to develop it. If it's stupid they will realize. If it's good they'll get enthusiastic.
In a previous comment I mentioned that this is the tactic that my manager uses, and it works wonderfully: let people talk from the beginning and ask questions later.
Of course, if you end up disagreeing, even though if their idea is good, they'll like that you let them explain and took time to consider