I *don't* know whether that's because the jumped in rigger control automatically overrides any lower-level attempt at control (as implied in 'Control Override' on p.265) or because the Control Device action cannot even be attempted in this situation due to the vehicle icon being replaced by the icon of the jumped-in persona.
It cannot be done because of control order.
If a matrix action require a device icon that is not there because it is merged into a persona icon then it can
also not be done because that.
1) Johann Corp leaves his Nixdorf Sekretär in a cab. Jimmy Decker finds it and wants to use Control Device to have the commlink send someone a message as Johann Corp.
Johann Corp will still have his persona formed on the commlink even if he left it in a cab and Jimmy Decker will still have his persona formed on his cyberdeck. Its not Jimmy Decker's commlink just because he physically touch it and Johann Corp will not suddenly be dumped from the matrix just because he doesn't physically touch his commlink.
If Jimmy Decker want to send a message while impersonating Johann Corp then Jimmy Decker can mark Johann Corp and successfully use Spoof Command.
2) Ronnie Rigger steals a company car from an Evo parking garage and jumps into it.
Ronnie Rigger does not own the car just because he is physically sitting in it. To jump into a device you don't own you need permission in the form of 3 marks and successfully use the Jump into Rigged Device matrix action. Either the legit owner or someone acting as the legit owner need to invite Ronnie Rigger to place three of his marks on the vehicle or Ronnie Rigger need a persona with an attack or sleaze rating and then either force or trick three of his marks onto the device icon by bending the matrix.
Sami Spider link-locks Ronnie....
Sami Spider first have to leave his host and then try to Spot Ronnie Rigger out on the Grid. Most spiders will probably not leave the safety of the host to attack icons out on the grid (they also doesn't have jurisdiction outside of the corporate host; his attack will generate overwatch score and within an hour GOD will converge on him).
...who is KOd by IC biofeedback.
IC cannot attack an icon that is not inside the same host as the IC. Ronnie Rigger is out on the Grid, jumped into a company car...
Can Sami use Control Device to drive the car back to the parking garage, or does the fact that Ronnie's persona is still there (due to the link-lock) prevent this?
You cannot Control Device a vehicle as long as someone else is remote controlling or if someone is jumped in.
Sami Spider can stop link locking Ronnie which will cause unconscious Ronnie to be dumped from the matrix and then remote control or order the auto pilot to drive home.
3) Goldenboy 2.0 (a metasapient AI) is floating around and notices Jimmy Decker's persona...
I need to read up on AIs before I can answer this.
4) Teddy Technomancer wants to help...
I need to read up on sprites before I can answer this (but if I recall correctly the sprite can help Harry when repairing his physical deck but not when Harry's virtual persona is hacking the Matrix).