To be fair, scarf is not my strongest pin. Cross-body side is my best. I could go into all kinds of details about the thoracic vertebrae, diaphragm, and hepatic compression if it was side.
Still working on making my scarf/kesa a more viable pin. My training partners are murderers with it, though.
Yep, getting your own hips too close will lead to disaster. I get pressure on the "floating ribs" and bring them to me as I go to them. It is a dynamic hold that can place the bottom man under a lot of pressure.
No matter if your sport has pinning or not, hypoxia makes cowards of everyone. I like the position as it gives me viable threat no matter where I am at. I go from cross-body, scarf, four corner, reverse scarf, etc. without every giving the man back space to breath.
Overall this is an underused position, that warrants in depth study. Systematically work it for several years and it will click in.