Since you can't later "Save & Apply" a shared segment, hiding the pencil would be ok. But knowing what contains the actual segment would then be not available/visible so if pencil is present then "Save & Apply" should be hidden or changed to "Apply" only.
Another better possibility : Add a new icon to the segment list: "Copy & Edit as a new Segment". That would be useful for any segment (own or shared) !
Thanks for the suggestion! Marking as duplicate of https://github.com/matomo-org/matomo/issues/7246