1) Is it possible, that these coins still belong to GOX? What do you think?
2) Have these coins maybe already been stolen in 2011 and were sitting on that wallet for so long?
3) Why is there no more motion since 6th of February?
4) Maybe all these 40k coins have been just bought by some customer on GOX and transferred to his own wallet. But then we should be able to identify some "cold wallet" in between of the the corresponding transactions, should'nt we?
1) Its "possible". I think that either they belong to gox (or Mark Karpeles, which in theory is DIFFERENT THING) or he was already lying and started its fraud at around that time. Anyway, the fact that most of those coins seem to have been static shows that either they are the stash of someone very wealthy which dont even need em yet or somehow lost access to them (temporarily or otherwise).
Considering the date it may also be KnightMB's stash, Finnley's "legacy",... maybe even sturle's... who knows.
In any case, we will be paying very close attention on any move of those coins in the future. And also there is an ongoing effort to compile as much data from different sources to get a better understanding of the whereabouts of these coins.
2) If I had to bet I would say they have always belong to same person/entity who has a bigger stash and haven't needed to use them yet. If they were theft at some time... We are still waiting for MK to report that theft, he hasn't.
Also... who in their right senses would have bought that stash and not move em to another address where only he has the private key? Unless that transaction was in fact the sale and he haven't moved since. Not the most plausible explanation.
3) You are mistaking in considering the recent "moves". It's all dust, I can also send some smallish btc to that addresses but that doesnt mean anything. It hasn't really "moved" since the time it was funded on 2011-11-16 05:59:08.
4) A lot of maybes are possible at this time. It's Karpeles which at this time should explain whose BTC's are those and why did he used them to "back up" his claims of solvency at that time. Whatever the explanation, he is or was lying. Pick your choice.