Is it possible? I just had a round where I fired an ARC rocket at a Mandalorian and a Sith was about 10 metres behind me. The rocket fired 180 degrees behind me, exploding harmlessly. There was no one in a position to push it in the it's path.
It is mostly about how push actually works with rockets. It is well illustrated on Helix's video.
When you push a rocket the game finds the point where your crosshair is currently aimed at (whether it is a wall, or another player's model), and then makes the rocket go from its current location in that exact direction.
With Helix, he died because he was aiming at a wall right in front of him. Most likely, something similar occurred to Sonichu - someone was standing in front of you when the push happened, and since the point where crosshair converged was closer to you than the rocket, the rocket flew in your direction, luckily past you in a wall behind.