Maybe he/she is taking the time to do that and that's why he/she haven't revealed the privet key
Let this be an indication of how secure Bitcoin really is .. as small as 120 bits out of the entire 160 bits range, 120 is still merely hackable by only 1 person on the planet with either unbelievable luck or rediculous resources. And that with the public key revealed. Imagine not knowing the public key. Imagine 121 bits or 122 up to 160 bits of difficulty. Satoshi really did think this whole Bitcoin security concept through. Hats off to the legend.
I can see it in completely different way ... It shows how UNSAFE Bitcoin really is.
The whole Bitcoin security lies in the fact that currently it is quite hard to bruteforce the whole range used for creating HEX private key.
So i could assume that Bitcoins security lies in currently used hardware weakness.
But that state will not last forever. In the end quantum computers will be able to crack all private keys where the public key is known (and there are many of such addresses).
Bitcoin security in its current form is TEMPORARY ... It's a matter of time.
Don't forget that every transaction you put into mempool means revealing public key ... so with quantum computer powerful enough to crack the private key from the public key in time-window when the transaction isn't confirmed shows that bitcoin is CURRENTLY safe ... but in long term its security will definitelly be cracked.
Seeing how hard is to acheive any change in BTC code now i would say that migrating BTC into quantum secure signatures can take too long to consider bitcoin safe.