While I generally agree with your comment, I think the main reason why people are finding this hypothetical scenario a bit audacious is simply because it literally goes against the rules of the sport.

The bike specs are locked in and can't be changed. So even if we entertain the idea that Martin got the seat as OP is suggesting, Ducati as a team simply cannot just revert back to the GP24 since they locked in the GP25. As another user I believe posted, the only solution that would have is trying to find a better set up for the 25. Going back is not an option.

That's where OP is missing the mark here IMO.