(a) A cotrustee who does not join in exercising a power held by three or more cotrustees is not liable to third persons for the consequences of the exercise of the power.
(b) A dissenting cotrustee who joins in an action at the direction of the majority cotrustees is not liable to third persons for the action if the dissenting cotrustee expresses the dissent in writing to any other cotrustee at or before the time the action is taken.
(c) This section does not excuse a cotrustee from liability for failure to discharge the cotrustee’s duties as a trustee.