I have really no idea on guessing who win this season because LoLo aside every remaining team seems have chance to win this. Tara & Joey and Matt & Redmond would be normal standard TAR winner, but we can't ignore Brooke & Scott as well because we have history of Flo & Zach and especially last season Dana & Matt as a TAR winner.
As long as they're not yet eliminated, London & Logan still have a chance to win. Some teams lay low for the whole race then give it their all on the final leg to win.
I don't think they mean they're out of it because of their performance; you're right in that some teams have had great final legs after a whole race of mediocrity (Freddy & Kendra, Josh & Brent, Amy & Maya, etc.). Given how TAR finales are typically set up (vaguely physical and/or flashy RB, vaguely cultural ARI, memory task, Pit Stop) L&L have a great shot, especially if Logan does the physical task and gets enough of a lead like last season's finale.
The issue is they have no story, be it them overcoming something or growing as people or becoming a stronger couple or anything. There's a weak suggestion of one in them talking about how they're a great, low drama pairing but like...Matt & Redmond and Tara & Joey do that better. Scott & Brooke have a different winner's path largely due to circumstance, but it's similar to how Flo & Zach or Matt & Dana were presented. Even other invisible winners (TK & Rachel, Kisha & Jen) had
something to them throughout the season.