If it's narrow to the point you post online about a recurring risk of being crushed while filtering on the left then it's most likely one of the places where it's not an acceptable amount of space to filter on the left.
But as we started - if you're worried about someone "swerving" to the left, they must be moving, and therefore you must be undertaking. Surely no one swerves their stationary car out of the way of an oncoming bike?
I mean yeah, it makes sense to filter up the right too, but it is acceptable to do it on the left