I considered a possibility: his hands—strong, capable of menace—are his favorite part of his own body. And your neck is his favorite part of you. When you choke his neck, you are using his favorite part of himself (your hands) to touch an extension of his favorite part of you (his neck).
He allows you to choke his neck, but this has never been your power—it is power he has lent you. Whenever he wishes, he can take it back with a single word: “Absolutely not.” In that moment, you will realize that all the “initiative” you thought you had was something he only let you believe was yours.
For someone like BB, a control freak, allowing you to choke his neck is the highest level of trust and "reward" he can offer. This is not you seizing control from him, but rather him temporarily "lending" his vulnerable part to you to play with—while the rules, boundaries, and when to stop remain secretly under his control.
Someone with an extreme need for control will occasionally "grant" you the illusion of counterattack, because he is confident enough that this illusion will never shake his true position. He lets you choke his neck not because you have conquered him, but because he has bestowed this privilege upon you.