The 'most of our coins' quote seems to imply they have probably indeed suffered a substantial loss.
I can't see them going bust for 5m bucks, though.
The major exchange in the West folding for 5m? VC money will need to bail it out - or lose 10M.
So - better than evens bet that they will survive - but BTC cred is again damaged.
Best scenario?
They have lost 18K BTC, but they just say - "everything's ok - we found them!" and swallow it.
Market bounces and VCs get some of their security back, and we're all happy. I don't think that will happen, but I wish....
If Stamp goes under - we are seriously fucked - but so are they.
Put yourself in their shoes - I reckon they will be trying to raise the capital, or even sell Stamp, or a portion of it.
I would. What's the alternative?