I personally find the Circuit Breaker unusable given my playstyle. I cannot use it. Period. I keep my primary equipped 100% of the time until using my secondary becomes necessary. If you’re charging the Circuit Breaker when a hostile approaches, the game breaks the charge and forces a melee.
Breaking the Circuit Breaker’s charge renders it unusable (obviously). And there are many situations where the enemy is too close (Cryo Archive) to use the Circuit Breaker (a CQB weapon) without instantly meleeing instead.
I think it's probably a good idea to use the player's input before assuming what the player wants to do. I feel like that might be the smart thing to do.