Your question touches upon a common theme: is pose X safe? The reason people may think a particular pose is not safe is because "It stresses such and such a ligament..." This statement ignores the reality of individual skeletal variation and the value of stress. Please read
this article to understand why all tissues need stress in order to be healthy, but too much stress (ie: to the point of pain) is never good, whether we are talking about ligaments or muscles.
There are many people who are naturally internally rotated so that Saddle will never be a problem for them. There are other people who are very externally rotated so that Saddle will never be advisable for them. Everyone is different and to say that no one should ever do Saddle pose (or any other pose) is clearly wrong. Beware of dogmatic absolute statements. Instead, check out each pose for each student and find the ones that work and are safe, and drop the ones that are not (those that create any pain.)
I hope the article helps answer your question.
Cheers
Bernie