You are a funny dude. All the balances you are seeing on your exchange account are just database entries and not actual wallet balances. Binance does not need an operational Symbol Wallet to allocate the Airdrop to your account. They just look at the trading data and XEM balances of each account and then add a database entry for your XYM balance.
So they are not sitting on their hands but are now actually implementing the Symbol Wallet into their System which will take some more days. Only the NEM Group is telling lies here when they said they are working with exchanges upfront for the wallet integration.
We're building wallet for Symbol. It is what Binance announced but we don't know what they are doing, are we? It can be a credited figure and they have yet built up their Symbol wallet. However, probability is they have built up the Symbol wallet and only hide your addresses, disable Deposit and Withdrawal functions. They will enable it as the schedule.
You can not investigate or verify what they are doing.