They owe you pay for the two weeks plus penalties (equal to one days pay for each day of delay) for not paying the final pay immediately at the time of termination, so they are "offering" for you to forgo pay to which you are legally entitled. See California Labor Code Secs. 201, 203.

EDIT: Though, the remote working arrangement and lack of US visa, even with what appears to be, from the given description, a valid employment contract (with offer, acceptance, and performance all having occurred) likely makes this less clear cut and, in any case, makes pursuing it more difficult, costly, and time consuming.

Fucking what? There is no "offer" to pay you for the two weeks. If you worked for them, they flat out owe you that money. That's an "offer" in the same way I "offer" to pay my landlord for not kicking me out.

You need a lawyer.

then take the cash, move on, and don't look back...in 6 months you will barely remember this whole event.

startups are risky...high risk high reward...it didn't work out but man, if you were good enough to be hired like that you can find 100's of opportunities.