I don't think that 50k is competitive for any developer that they would be willing to hire, regardless of where they're located or how much they promise the equity will be worth in a few years.
Edit: Didn't even realize that it said you had to relocate to SF. For SF, one of the most expensive cities in the US and the one with by far the most competition for developer talent, 50k is not competitive under any circumstances (It's barely livable.), and even 100k isn't very competitive for anyone with even a little good experience.