Forgive my ignorance, but if the address (Satoshi's genesis address) contains the unspendable BTC, does is mean other Bitcoins that get there become unspendable as well? Of course, these coins aren't likely to ever be accessed anyway, but, assuming Satoshi is alive and didn't lose access to anything, would Satoshi even be able to use those coins? pooya87 says it's possible, which gives some hope these coins aren't just burned.
IMO, if one has such money to spare, it would be better to donate it to a good cause instead of burning. I don't think it was done by mistake, though.