are you a BT broadband customer? so you have to open window and stretch out to touch cable so why not safe? there is no electric power in cable so no possible shock
If I remember right the Low Flying Wires Act says a Drop Cable needs to be at least 2m from a window.
Is it your house/install or for your neighbour?
Probs need to contact Openreach, assuming it’s there’s and not an Alt Net’s to see if it can be moved or raised higher using a Swan Neck or something.