A grounded pickle. The word grounded is very important here, and missing from the question in the title.
Even if the tower is off, if it's near any other sites, they can draw a significant amount of RF (as a good AM tower is a good AM antenna) and if it's not grounded, that RF will go through a person too!
This specific tower site doesn't require lights on the shorter towers, so it's not an issue here, but for sites with lights needing replacement, most nowadays turn off power to the tower and ground it before anyone climbs the tower.
I imagine this inspection work is done with camera-equipped quadcopters nowadays.