if somebody takes it in to safe-keep and leaves a message at the location they took it, how to contact them. Sort of what johoe did.
There's no method of doing that in Bitcoin.
Of course there is. The blockchain is a public ledger. Sweeping coins to an address and then posting about it and the address is exactly that. The word will spread quick enough, as was shown in johoe's case.
Also, by posting that there are more flaws to be found at bc.i you just gave the black hats a motivational boost.
There's existing incentive of being able to steal millions of dollars worth of Bitcoin. Do you really think some terse comments confirming that there are issues will make even the slightest difference? It's very much public knowledge that there's huge problems with their management of security, else this thread wouldn't be 20 pages long and I wouldn't be posting here.
Yes, I think it makes a difference. This thread is about the R values. You claim that there are more flaws to be found. This could be motivation to poke around some more.