You should rethink your decision to stop GoxBtc trading because of MtGox closure. Many people has GoxBtc stuck on your site, but there may be still people interested in buying or simply trading GoxBtc as a reflect of market sentiment towards MtGox. As an example, thanks to the announcement of the 200,000 Btc wallet recovery, some may give a 25% chance of recovering Gox funds, which is way higher than the latest GoxBtc traded value (below 10%).
We already know GoxBtc aren't backed by real Btc, as most altcoins are also backed by thin air. It's all a matter of expectations.
Please resume trading and let some of us the chance to recover our stuck funds, at least partially. An unilateral decision like the one you did is not any better than Gox decision to halt withdrawals, in my humble opinion.
I think too trading could resume at bitcoinbuilder, but after all, that's up to the site owner to decide. Closing down trading might be the safe deal - if he lets trading continue, and then eventually Gox does not reopen it's door or do not pay back any btc, some people may as well direct their anger at bitcoinbuilder.
It could also be argued that as long as bitcoins cannot be transferred internally at MtGox, letting trading continue is not a wise move. How can the market trust that GoxBtc does exist, and will be delivered?