Will this tie-down do any good?

If you used thin fishing line and not FAT SOFT garden wire, you risk guillotining you plant. Once my tomato cage wire snapped heavily bent plant.. I would bent more, way more. Target is to brake dominance of main top. It should be lower than rest of canopy. Most of my grows are with LST. Check this for example : growdiaries.com/diaries/27468-dr-krippling-incredible-bulk/week/129882 There is plenty of knowledge, how to bend, where to position, how to plan all LST for having enough space for all branches around pot. Done wisely , it does magic. Some say anchor main stem, i usually did without. Never let leaves touch medium, they sweat otherwise and troubles starts .. Tuck leaves daily to expose side branches for light. Tie girls ONLY on watering day, otherwise you risk to snap something. Do it and then water girls...