lastlook: considerOrderERC20 checking against server pricing?

Hi. 
Looking at the LL implementation, seems the above method verifies such data points as sig & token balances/allowances. However, cannot spot where it validates that the order actually matches a pricing. So, could a client interacting with that server post an order setting `senderAmount` to the server's max allowance of some token with `"signerAmount": "0"`?