When PF they are Acting In Command Under Supervision
Since 98 percent of the flight is flown by the automatic pilot it seems a bit rich to log the lot as ICUS. ICUS is really nothing but dual instruction under a fancy status title. And by the way I believe in UK, if the real pilot in command disagrees with any decision made by the copilot logging his leg as ICUS, the ICUS is automatically downgraded to copilot time.