Why "100% tie-off" is a fall-protection term meaning the climber is never unattached from the structure. In practice a climber wears a harness with two lanyards, so while one is unclipped to move past a guy bracket or other obstruction, the other stays attached to the tower. There is never a moment during the climb, the work, or the descent when nothing is connected.
Watch out Securing ropes, guys, or tools is good tower housekeeping, but "tie-off" in safety language refers to tying the person off, not the hardware. Locking out breakers is electrical lockout/tagout, a different procedure.
100% means 100% of the time the person is attached. Two lanyards so one is always clipped in.