How does a picture taken in this room support the assertion that staffers have access to SCIFs which are entirely separate secure rooms not used for emergency meetings?

And let's clarify staffer. I would expect that Pres and VP staffers have that clearance because their bosses do.

The Situation Room is a SCIF. The picture is clear indication that staffers are allowed to go into SCIFs - there are staffers that are shown in the picture, and the photographer himself is a staffer. Only people with adequate security clearances are allowed in (and only for the purpose of performing their duties), but that includes a lot of upper-level staff.

And remember, documents have to move in and out of SCIF's all the time. The White House SCIF doesn't always and forever contain every SCIF-level document the President might need to review. If someone takes notes of a meeting in a SCIF, that doesn't mean those notes have to live forever in that SCIF and can never be removed. Documents have to be able to move from SCIF to SCIF (or the Departmental facilities where they're normally stored). People need to bring the SCIF documents into the SCIF for the President to review, and then return them to wherever they are permanently stored afterwards (which would also be a SCIF). The President isn't carrying his own documents around, and neither is the Vice-President.