I think I’m not understanding exactly what you mean by “slow down, clutch in, shift to first and then use brakes.” Are you holding the clutch in the entire time as you brake from high speed to low speed/stopped? If that’s the case, I wouldn’t do that, simply because if you suddenly have a need to be in gear and get moving, you now have to take the time to sort out what speed you’re at and change gears to get there. That’s a pretty ‘high’ cognitive task in the middle of a sudden need to be quick.

Also, most motorcycles will have some degree of wear on them at some point, so you may in fact not be completely removing the clutch’s connection between wheel and engine. Imagine the transmission as six (or four/five, whatever amount of gears you have) different gears, each spinning at different rates depending on your rear wheel’s speed. Even if the engine isn’t transmitting power through the clutch into the shaft, the first gear is going to be spinning incredibly quickly if you’re shifting into it with the dogs of the shaft at speeds higher than it is usually shifted into. If the difference between the gears is large, as it would be at higher speeds, and your clutch is still transmitting some power because of wearing/stretching cable or the myriad other ways a clutch can weaken, that won’t be good for the transmission’s life.