nope - no way to alter a player's unitpos in any way
You could setpos them instantly 2 meters above ground
level, but:

how would that look like.
Nah - really now: hiding in a bush is what most of intelligent
human would do, once the first bullet starts flying.
Ah wait:
make your CTF on desert island, AFAIK there are no bushes
to hide in, and digging in hasn't been implemented in OFP yet. ;D
~S~ CD