A lightning storm is approaching. Standard operating procedures are
to detach antenna from equipment, and then "attach the antenna to
ground".

Maybe they are talking about outside operations at the base of towers.
I'm just interested in what to do, without leaving my room, about the
dangling cord I have just detached from equipment. Seems to me if I
attach it to ground, it will just make the antenna more attractive to
lightning strikes, vs. just leaving the cord dangling.

Maybe I will let the end dangle 30 cm from grounding metal, and away
from everything else.