Doesn't make sense -- honest
When I came to work in the US these sorts of companies were "citizens only" -- I think the reason I got work here was that the Reagan era military buildup literally sucked all the citizen engineers out of industry leaving a vacuum for us aliens. Over the years the rules seem to have relaxed to 'ciziens and legal permanent resident" but the idea's still there. You need to have a stake in the country to be working on its sensitive technology (and SpaceX does have sensitive technology). SpaceX's policies in this regard are right on the money even without the rather nitpicky questions about qualifications and whether people allowed into the country temporarily are actually seeking to immigrate (in theory someone seeking asylum is just looking for a safe country to stay in, they're not would-be immigrants seeming to game the system by bypassing immigration rules. ("Wink, wink......."))