What would it take to set up a functional pro-rail advocacy group, and how would you keep it from degenerating into a cult of personality? Most such groups are set up by somebody with A Big Idea, and stay alive by providing entertainment or other return to the Paying (in one way or another) Members. If effective advocacy is defined as getting something for those members, which it is, really, then any benefit to the public is incidental.

If expensive projects to bypass certain choke points could be built (long since defined and partially designed, but not funded and unlikely to be in the near future), you should be able to get an express from LAX (Union Station) to SD in less than 2 hours with, possibly, as many as 3 stops. 1:30 would be pushing it with only 90 mph top speed unless nearly all spots with speed limits under 70 are eliminated and there are No Stops.

With the current line, at times of little congestion (say, mid-day), an express (no stops) run should be able to approach your old San Diegan time, but lack of intermediate service would limit its potential ridership. Also, the old San Diegan line ran at a time of less traffic and MUCH less regulation - I'm certain that speed limit observance was less strict, for instance.