Are you located in China? Is the selfish miner located in China?
He claims to be named LiYi, and located in GuangZhou, China.
2 - Individual miners may not have standing to sue the selfish miner. In a civil case (involving money/damages) you must prove that damages be caused, but also that he damages were against you. There is clearly a relationship between the miners and the pool (the miners provide work for the pool and in exchange for each unit of work the pool provides a maximum amount of payment, if payment is less then the maximum then when the pool can afford to pay more then the maximum the units that got paid less get paid more). The relationship between miners at the pool are not as clear. I am not an attorney, but I think a likely ruling would be if a miner tried to sue another miner at the same pool, the judge would say that their "beef" is with the pool operator, not the selfish miner. On the other hand if the pool operator were to sue a miner the damages are more clear, as the miner did not provide the work, the miner said they provided the work, and the pool operator paid for the work that was not done. There is clearly a fraud here.
Pools don't pay miners for work, merely coordinate cooperation between miners who pay each other.
This is especially clear-cut on Eligius, where most of the funds never pass through the pool operator's hands.
That may be how it is on a logistics standpoint, but is that how it is in the eyes of the law? If you were BTC Guild or ghash I would say defiantly no, as both of those pools have block rewards (and tx fees) paid to the "pool" wallet, and the BTC is then eventually transferred to miners' wallets via automatic payouts. Eligius is very different in that it pays the block rewards (and tx fees) directly to miners via a TX in the found block. Someone could argue what you are saying but they could also argue that since the pool determines who gets paid how much via the payout cue (this being embedded into the header of work provided by the pool - I think this is how it works) that the pool does really control the found blocks. Even a attorney could likely not answer this question with certainty, as I don't think this kind of dispute has been litigated before. The only person who can answer would be the judge that hears the case (and any appellate panel of judges that hear any appeals).
I know for tax purposes, other pools are using this same interpretation.
In theory he paid good money for this equipment.
Supposedly he made it all himself.
That means his primary cost is electricity (actual chips and PCBs do
not cost very much to produce).
As far as I can tell he has done this to multiple pools. Do you think it would be possible to modify mining software so that only the stratum shares are sent back to the pool with the correct header, but the other shares could use a different header (one that pay out to another address)? Do you have a way to determine when he withheld a block from the pool? If so can you compare that to other blocks found around that time, is there any consistency as to who found the blocks? I know that it has previously been determined that you cannot modify block headers to make a found block payout to your own address as the hash would be invalid, but someone who has the resources to have millions of dollars worth of mining equipment might have the resources to make this happen.
It's not possible. I don't understand this part of your post entirely.