To me spawntrapping is camping at a spawn without any awareness of how the game is proceeding. You sit at a potential spawn and hope the game progression will spawn opponent in front of you.
OTHO, if I have good map skills and are able to dictate enemy spawns by my play and I timely position myself at their spawn, then it's just good skilled gaming and too bad for the enemy who doen't fight the instinct to blindly run right after the moment they spawn.