As with most targeting effects that have specific conditions, if the targeted card is flipped face-up in a chain (for example, if it is a monster and “Ceasefire” is activated, or if it is a Trap Card and is chained to the effect of “Granmarg the Rock Monarch”), then the effect of “Granmarg the Rock Monarch” disappears.
The effect of “Granmarg the Rock Monarch” is an effect that targets. You select the targets when you activate the effect.