Since this is a privacy-oriented, it may be possible to disable Bluetooth permanently by modifying the speaker. These options are risky, and could easily result in a non-functional speaker.

Option 1 is to disable the pairing button. If it’s a rubberized button with the contact pressing on the circuit board, you can put electrical tape over that portion of the board. For touch sensors, you could try removing the wiring, but you risk disabling all buttons.

Option 2 is to disable the Bluetooth. You can attempt to remove the antenna or possibly just cutting the traces (metal lines) of the antenna. If you can identify a separate Bluetooth chip, see if you can remove the power to the chip. That could be as easy as desoldering the input pin and lifting it off the pad slightly, or cutting the trace entirely.

This is the snail immortality thought experiment. You are immortal until a certain immortal indestructible snail touches you. You can never be rid of the snail, and it will never stop pursuing you.