Zemo would of have control just like he was able to brainwash Winter Soldier again. Also, again.... it is stupid to so-called kill yourself after an assumption of dividing the Avengers when the Avengers were already divided by the Registration Act. Which again he should of JUST sent the tape at the beginning to Stark.... it made the stakes for the entire film more impactful. The fact that he somehow KNEW that Stark will show up in Siberia is terrible writing because there's no rhyme or reason for it...or anything else regarding this film.
If anything, it should of been about Zemo sending the tape to Stark.... Zemo then brainwashing Winter Soldier...and THEN the Civil War to include the airport scene making everything at stake FOR REAL rather than the last ten minutes of the movie wasting our time the whole other 2hrs of the film of mostly filler scenes.
I do think the plot would've been more interesting if the Stark/Bucky reveal happened in Act 1 so the rest of the movie is Tony and Cap fighting over it, but that's besides the point.
You say the Avengers were already divided, but there's a difference between being divided and being torn apart. The disagreement over the Sokovia Accords wasn't enough to break them up, it had to become
personal and that's what Zemo achieved.
And Zemo didn't get the tape until he got to the base, at which point he was already drawing in Steve and Bucky. Yeah, some of the shyt that follows is plot convenience but there's nothing in the movie that suggests he wouldn't have sent the tape to Stark regardless. What do you think, that Zemo was just gonna chill in that bunker until someone finally decides to show up? You gotta think further than that.