On one hand, I think the perpendicular movement cheesing technique requires a bit of understanding of orbital behavior & the firing trajectory overall. On the other hand, this alone probably should not allow full-game cheesing.
Perhaps placing a bumper object that can rebound bullets based on collision angle in later levels could help resolve this somewhat. I do think understanding orbital behavior should be the key to player success in this game, though. So to an extent, if the player can figure out how to orient their movement & shot angle from a preferred starting point to cheese, that could itself be the point the game makes. I’d probably increment up to 2-3 bumpers at max if you decide to do this, as any arcade-y difficulty introduced this way would also reduce spotlight on the core identity of the game.