I'm sorry, but I'm still not understanding the basis of your conclusion that Trip didn't understand Phlox's explanation.
Anyway, it's obvious that he didn't get the explanation whether that was before or after he said the line is of little relevance.
If he said the line after the explanation, I can see your point that he would have appeared to miss the whole thing about the possibility that if they could change the past by eliminating the spores, Earth might be saved, and not be "gone." But at this point, he had no details about Phlox's experiments at this point.
Plus I didn't say WHEN he said it. I said that that's ALL he said.
Actually, he has several other lines in the scene after Phlox's explanation. Phlox and T'Pol have called him to Sickbay because Engineering cut off the power Phlox was using for his experiment, and Phlox and T'Pol make their case to Trip that Earth could be saved if Phlox can continue. They explain about the parasites, and the chance to change the past and save Earth. Phlox can't guarantee success - he and T'Pol use qualifiers like "may" and "could" and "it's possible," because they don't know for sure themselves. But the stakes are crystal clear.
T'POL: History may be altered. Captain Archer will have remained in command of Enterprise. Our mission in the Expanse could have an entirely different outcome.
PHLOX: We only have to divert power for a few hours. I am certain I can complete the procedure in that time.
TUCKER: I'm sorry. We need all the power we've got for the weapons.
T'POL: If the Xindi are on their way there's very little we can do to stop them..
TUCKER: Well, we can't just run up the white flag.
From the looks of this dialogue, Trip may well have understood Phlox and T'Pol, but still had to weigh this "maybe" procedure against keeping the ship as fully powered for battle as possible - and in this timeline, they're in the middle of a war.
And his insistence on refusing their request to use these resources on an action that was meaningless is pathetic.
Sure, you can disagree with his decision. One of the tragic consequences of Archer being disabled was that Trip's vengeful attitude toward the Xindi for killing his sister -- and we see his fury early on, in "The Xindi"-- has not been tempered by T'Pol or taken over by Archer, since they were taken out of the picture. His fury has eaten away his compassion, and he's driven by his hate for the Xindi in "Twilight." As a commander in battle, it's understandable that he would choose his weapons (being without them for "several hours" might mean certain defeat to him) rather than leave the ship vulnerable while Phlox conducts an experiment that "could" or "may" work.
"Twilight" is a tragedy. Archer, Trip, T'Pol, they're all broken because of it. That's the point. They all die in this timeline, Phlox too, but they're all trying to save humanity, even Trip, the hardened, cynical war commander. A big part of why I love this episode is that the story puts our main characters under terrible pressure, and we see their truer selves - we even get to see what they didn't have a chance to become, in the original timeline, because of those parasites in Archer's head. In contrast, Trip in "The Forgotten" still has the compassion to stop hating Degra, and the support of T'Pol, which enables him to finally open up and grieve for Lizzie.
I'm not here to change your mind or dismiss your opinion, but to examine the issue. I've learned a lot from you during this discussion, since I took Phlox's lack of certainty as justification for Trip, the battle commander, to credibly refuse to divert the power from his weapons. There's more going on than what I took away from my initial viewing.
