Apparently. To repeat: D&D rulebooks have always been oddly coy about the authority of the GM to frame scenes, in various circumstances.
The contrast with rulebooks which are not coy about this is pretty marked.
For instance, this is from Marvel Heroic RP (p OM34):
A pitched battle across the frozen wastes of Jotunheim and a tense diplomatic meeting between agents of the Shi’ar and Kree empires are both examples of Action Scenes. An Action Scene might begin in medias res, in the middle of the action - Thor and his Warriors Three are already in the midst of a titanic battle with Frost Giants, or Cyclops and the X-Men are already three hours into the middle of the diplomatic encounter. What’s important is that this is where the real action starts. . . .
If you’re the Watcher [= GM], you get things started by establishing who is present in a Scene and where. This is called framing the
Scene, and it’s your chief responsibility in the game - other than playing the bad guys, keeping the doom pool, and rolling opposition dice. You should ask directed questions of the players, encouraging them to describe what their hero is doing or how they plan to respond to something. Rather than asking, “Where are you?” try something like, “Are you in the middle of the rank-and-file, or are you with the officers near the rear?” You might even establish a particular fact at the same time: “You’re with the officers of the Imperial Force. How did you agree to this position?”
If you’re a player, you should allow for some relaxation of control over your hero for this purpose, because after this point everything you do and say is up to you and the roll of the dice. If the Watcher asks you, “How did you agree to this position?” use that as an opportunity to build on the story. You might say, “Cyclops wants to see the big picture, so he’s staying back to be sure his tactical genius is put to good use.” Or, “Cyclops doesn’t trust the Shi’ar officers, so he’s staying near them in case they decide to pull a fast one on his team.”
That's a really clear statement of who has what authority in relation to framing scenes.
Is Cyclops's decision about whether to be at the front with the troops or in the rear with the officers external to the actions of the PC, or not?
The MHRP text is clear about this. (And other bits of the text make it clear when and how the GM can starts a scene with the PCs unconscious.) Is the D&D text comparably clear?