If all vehicles are limited in the same way I am uncertain how this could even happen.
If the computer enforced max speed is 120km, and I'm going 120km, and the vehicle coming up is also going 120km, they can't overtake you, they can't close the gap.
Maybe, if the vehicle ahead of both of you is going much slower than either of you then yeah, they could close the gap. But even in that situation you could speed up to the max speed, matching that of the approaching vehicle, and merge. You'd still need to slow down to match the vehicle ahead, but so too would the one behind you, regardless of what you were going to do.
If the computer enforced max speed is 120km, and I'm going 120km, and the vehicle coming up is also going 120km, they can't overtake you, they can't close the gap.
Maybe, if the vehicle ahead of both of you is going much slower than either of you then yeah, they could close the gap. But even in that situation you could speed up to the max speed, matching that of the approaching vehicle, and merge. You'd still need to slow down to match the vehicle ahead, but so too would the one behind you, regardless of what you were going to do.