If you shape a branch, you typically want to keep it tied down or whatever you used to train it. Those 90-degree benders you can buy do need to be taken off before the stems grow too thick and damage themselves.
The stem will become rigid at some point and maintain it's shape, for the most part. But, even then it will try to bend upward over tmie. I used to have a before / after of a plant that was mostly horizontal to start, but has a ~30-degree angle by the time it was harvested.
At some point you do stop LST'ing the top of the branch, when it is sperad out or in the position you want it to be. Then, you let it grow vertically like any other cola.
Your internodes look tight. I'd back off on light a bit. or it's got a case of dwarfism. You don't need that many branches so tightly together. will only cause problems. A little more internode length would do you good, and that's a direct effect of light intensity.
defoliation is rarely needed, in this case you amy need to thin some spots out due to congestion. again, one of the negatives of nodes being too tightly packed together. As that axillary branchign goes out, each one will have sets of leaves growing out and almost certainly all clogged up, touching, overlaping, creating condensation / standing water on the leaves which will lead to mold.
any axillary growth pointing down into dirt can be removed, that will help a bit.
to avoid these sorts of situations, it's better to plan and work backward from an intended canopy. You want about 3 colas per sq ft to maximize yield. If you need 8 colas, then you train and work twoard that goal spreading out 8 strong branches. Keeping them level will even out growth. break apical dominance of anything that outgrows the other branches etc... easy peasy. This is more of an option for photoperiods than autoflowers of which you have zero control over their vege phase length. Just stuck with what it gives you.