There isn't currently as far as I know a non-stop between LAX and SJU - however, before the choosing the flight stage, when you are simply entering the city pairs if you try LAX-SJU-LAX you get the following message "You can make only one transcontinental flight between East and West US cities - East: Baltimore, Boston, Fort Lauderdale, Hartford, Miami, Newark, New York, Orlando, Philadelphia, San Juan, Toronto, West Palm Beach, Washington D.C. West: Las Vegas, Los Angeles, Long Beach, Oakland, Portland, San Diego, San Francisco, San Jose, Santa Ana, Seattle, Vancouver. Please select another destination"
This of course harks back to the "old" cities rather than states rule - but nonetheless it is still saying (at least for online bookings) that SJU is subject to the restrictions.