Stopping in a turn can be difficult because:

Question

It is possible to use both brakes while turning, but it must be done with great care. Some of the usual traction is being used to make the turn while the motorcycle is leaning, so less traction is available for stopping.

Accepted Answer

There is decreased traction available for stopping while the bike is leaning.

Answer

The rider is usually focused on the turn and not on the braking.

Answer

The brake controls do not work in turns.