Having used Google Chrome for a long time, I've previously taken it for granted that multiple tabs in a given browser window can be selected, either one at a time (Ctrl-click) or in a contiguous range (Shift-click). (The main reason one would do this is to drag multiple tabs simultaneously to a new browser window, or from one window to another.) I'm giving Mac Safari a chance to win me over, but the very basic functionality of selecting multiple tabs appears to be completely absent. Am I missing something?
Having never needed or even thought to do this I see the behavior you are talking about. And I believe the Safari engineers may have been of a similar mind.
I see no combination of keys that will allow you to select multiple tabs, so I am thinking that may not be possible out of the box with Safari.
That does not mean that there is not an extension (Plug-in, in Firefox lingo) that might provide that functionality but I am unaware of any that do this. You may be out of luck.