Hello Flex, or unflex as the case may be:-)
Yes tight shoulders appear to be more common in men, though it depends fully on the lifestyle, path, work, and processing they’ve done. So it is not inherently so. But as you point out it is the culmination of choices, not gender.
“Doing” unassisted backbends is far less critical than doing backbends (of any sort) with integrity in the physical body. But that’s not the point of your post.
You’re asking about a pose from the Ashtanga series. And as I’ve said here numerous times, this should first be posed to the teacher that has been selected by the student. Of course if that were always the case I’m not sure there’d be much of a yoga forum
Frankly, if the body is not ready for a pose, or a segment of the body is not ready, then try it, of course. But generally not ready is not ready. The yoga that I share with others is not ashtanga yoga. However if I had a student in class with this issue in this pose I would first suggest holding a yoga belt between the hands.
I’d also like to point out that there are precursory poses, actions, philosophy, warmings, etcetera that lead up to doing the pose you mention. Perhaps those are built in to the sequence and perhaps they are not. It is not for me to say. So again for my students we do several things specifically to open the shoulders in preparation for such a pose.
You ask about “off the mat”. Yes there are things to do off the mat. The first is to make life choices that do not place the weight of the world on your shoulders. The second is to process, through meditation, your response to that weight of the world (when you are unable or unwilling to un-choose it).
The diet and lifestyle we teach in Purna Yoga™ teaches us that altering what we do with our bodies, how we do it, and what we put into it to nourish it also has effect on the the body’s systems.
Do shoulder opening poses (not ones that require openness)
Stay hydrated, alkaline, and oxygenated in your eating
Meditate and see what you are still bearing
Rub organic, untoasted sesame seed oil on the deltoids morning and night.
These things, when done from a sound intention and done with sincerity, will be very helpful.