I don't think so. It doesn't take anywhere near ten turns to get to the transponder.
You've obviously not seen my rolls against the darn imps and piggies...
Anywho, this deterioration of the timer for pre-fight actions could make sense for like an optional thing for Custom Mode and/or built into Honour Mode. But by default it won't make sense. As it's the tutorial area, people who are new to the game will be figuring out the games systems. Maybe they get bad rolls in the fight. Maybe the accidentally knock down some of the caustic pods and create a massive fire they can't get past for several turns. Maybe they get AoO'd by Lord Firesword. Etc.
There's plenty of reasons why a new player might not reach the transponder in 10 turns at which point they're being actively punished for doing what the game promotes... Which is exploring and interacting with things.
It would also set an unreasonable precedent for expecting time to be a factor while playing the game (Which it's not, you can spam long rests to your heart's content and it doesn't impact very much, I think only Nere is actually affected by passage of time from resting)
I think you're exaggerating about your rolls.
That aside, why 15 rounds instead of an infinite number of rounds? It's not like 15 is the scientifically exact number of rounds necessary for something something words something. If it were already ten and I were arguing for five, I suspect your argument would remain the same, as opposed to you suddenly declaring a need for five more rounds. See what I mean?
There's a limit to create a sense of urgency. To make the player sweat and feel the heat of the moment. This suggestion just expands on that concept, making it a bit more immersive and noticeable for folks who replay the game. Otherwise, it probably wouldn't even be noticed by a first/only-time player.
Anyway. I would add the following two things:
1. It's highly unlikely Larian would ever take this suggestion. I'm putting it forward as an idea because I think the game would be better for it, but I'm level headed enough to understand there's very little benefit to do this for Larian. I mean, i think it's a good suggestion, but I don't think it's *that* good of a suggestion. It's not like the game would suddenly be ten times better for the effort.
2. I did put forward the suggestion thinking about Honour Mode. I have less interest in Story or Balanced play, and, as such, I don't think I'm necessarily qualified to give feedback for those difficulty settings.