The Force will never be fully understood. i do not think that Yoda himself could understand completely the Force. And Luke, by choking the guards chose the easy path. no matter the intention, harming someone is evil. if the intention is to protect someone else then the evil becomes less. It is still evil however. Let's say something extreme. Some politician wants to solve the problem of AIDS. The extreme solution would be to gather all those people, and execute them, to make sure that the virus would not torment humanity anymore. His intentions are good. Is he lightside though? Think about that