Yes, Tab Stash explicitly ignores pinned tabs, because pinning a tab usually indicates a desire to keep the tab open and available at all times.

It sounds like you might have a different way of using pinned tabs, and I'd like to hear more--how do you use pinned tabs, and when would you want to be able to stash a pinned tab directly (without unpinning it first)?

If you'd like to share any thoughts on this, I'd love to discuss in a feature request: https://github.com/josh-berry/tab-stash/issues/new?template=feature_request.md