Ian is almost certainly on an incredibly dodgy legal footing, having made huge profit by perpetuating fraud.
So yeah, I'd sue him if I'd been dumb enough to put money into this scheme.
When you had an account with BitcoinMax your contract partner was Ian Grice (paybtc/E&G). So maybe it would be the best to build a legal case against Ian. That way he would at least most probably start to respond.
At one point in time Trendon wanted to have the accounts transfered to him. If Ian had complied, you could go direct for Tendon. Unfortunately, or deliberately?, Ian decided to protect Trendon and keep the accounts. Now Trendon has an additional shield, because only Ian had a contract with him, and Ian is apparently no longer interested. I assume he had profited enough.
Or maybe he has not sent coins (all or just a part of them) to Pirate at all. If you knew right from the start that Pirate never planned to pay back, you could add your own scam on top of it. With the result that the blame goes to Pirate. He just needed to pay the bit of interest which investors requested, something that worked out fine as long as new investors joined; and that worked until Pirate defaulted. With his explanation of "coin ownership change" (see below) he broke the traceability of coins. So even if you could prove that an address holding BMax coins is under his control he could simply say that's because he invested the amount from his other wallet. With this in mind it would be foolish for him to officially acknowledge BMax balances because during a lawsuit it would show that his BST account had less coins than the sum investors sent to him.
an example of that would be let's say to start with i have 200 btc which i keep here:
BST wallet 100 i own 100% of these coins
My wallet 100 i own 100% of these coins
then, a bitcoinmax lender decides to invest 40 btc (sending it to MY wallet), the ownership changes immediately to:
BST wallet 100 i own 60 of these coins, and the bitcoinmax lender owns the other 40
My wallet 140 i own 100% of these coins
then if BST stops paying, i've lost 60 btc, and the bitcoinmax lender has lost 40 btc, even though the actual 40 bitcoins that he sent are still unspent in my own personal wallet.