I like what BNM says, with a segmented move, though I have to say, this lady that called sounds like she is trying as hard as she can to scare you away. If I were you, I'd give her/your boss a call, and talk to him about job security. Perhaps you could work something out, where they are contractually obligated to employ you for X amount of time, provided you show them that you have high enough quality work done before hand.
Basically, if the company pays to transfer people there, and then within two weeks, 90% of the new hires get fired, there's something wrong with the place. I can't imagine what it is that is going on, but either someone has lied to you (or twisted statistics to their liking) or something really is wrong with the place. You should let the management know that you think someone there has deceived you in some, because you felt the arrangement you had was adequate, but feedback from the relocation department basically says that your job and future in San Diego is already in jeopardy, and you haven't even started day one.
Essentially, all I'm saying is that you don't want to walk into a trap. If you talk to the boss, focus on what you liked about the place, and how you thought things really fell into place for you to move there all at once. Make it clear that you aren't expected anything more than what you've previously arranged with the company, but make sure you receive some great assurance that you won't lose the job in two weeks without some sort of freak accident happening, and the whole company collapses into the ground. If their turnover rate is truly that high, you don't want to work there, at all. If it is, there's obvious some rare quality or performance aspect that they expect every employee to know, but only few do. You might want to see the composition of schools that reinforces their employment. Perhaps the rare few that stay at the company all went to the same school and learned specific ways how to do something, I don't know, but that rate is not at all what anyone would want, unless he or she is extremely desperate.