Agree, the BOAC sector from JFK to San Francisco had been given up by 1971, the timetable shows a connection on United. The route onwards, ultimately to Hong Kong, was doubtless worth retaining. The 707 did indeed have to get there the long way round, outward via Asia.
San Francisco to Tokyo on BOAC always routed through Honolulu rather than direct, but it was still a bit of a stretch across the western Pacific and I believe even the inaugural 707 had put in at Guam, although it was never shown in the timetable.