However if a pool op wanted to hide it all they'd have to do is when they won a bitcoin block don't send the solution to the aux chain. Then there's no link... They lose 1 block on the aux chain but they get all the aux chain blocks that meet aux difficulty but not bitcoin difficulty, which is most of the.
Nonsense. Everytime pool is doing MM on BTC network, his coinbase is different (much longer) than usual. So you can detect if pool is doin MM, lets watch "raw data" of his blocks. There's no way ho to hide this information.
Example of coinbase while merge mining: http://blockexplorer.com/rawblock/00000000000008371089fddbdee1f7cf580d98e64c276c649102d2ab95fd9844
Fair call... A pool op would still have plausible deniability. You can insert any old junk into the coinbase. Correct me if I'm wrong but the MM specific stuff in the coinbase is the merkle root + tree size + nonce so with a random nonce the only real signature is the tree size and length of the data.
However, plausible deniability is probably largely academic since any pool up with unexplained data in their coinbases will no doubt come under suspicion now.
BTW this looks wrong to me: coinbase":"045dee091a03ac8701522cfabe6d6defb6519b6439e5852d2cdba258fe21438204f3eb6f69001fc
it indicates a tree size of 0?