My experiences with runts is they aren't worth the trouble for the space they consume, I had two this year one was because of root rot the other was apparently just genetics, the root rot plant I saved finished but the yield may have been a 1/4 oz or less, the other natural runt produced good bud but maybe 1/2 an oz.

There are a lot of different opinions on pinching and trimming. I find that bending the tops down about 8-12 inches from the top will help you produce a new string of cola buds from the bend to the end of the tip and gives you a little more grow room. I'm stripping the bottom branches(about 18 inches from the soil) off of my plants even outside, from experience they seem like more hassle then they're worth and produce small clusters of loose buds with the theory being the plant isn't wasting energy growing those branches/buds out. Like I said there are a million theories on pruning, my advice is try bending it's interesting to see 4 new vertical cola buds growing.