This is correct. California requires concurrent didactic and clinical experiences. As an example, if you're doing Peds in class, that same semester/quarter you must have Peds clinicals. This requirement doesn't just affect Excelsior students, it also affects some other US and overseas students as well. Philippine students have been impacted greatly by this, not all, but many.No personal experience, but California does not accept Excelsior.
If a nursing program basically follows the basic California pattern for didactic/clinical experiences, it'll likely be OK enough for its students to be licensed by California. Excelsior doesn't (and won't) follow this pattern, so their students are SOL for obtaining a California nursing license. I'm not saying that Excelsior is or isn't a good program, just that their graduates WILL be limited in where they can work (not California).