Type of Collateral: My BITGO Wallet, where I am holding around 0.4 Bitcoin, you will receive Password + 2FA , you can change the Password and set the 2FA for yourself, but you are strictly not allowed to move out any funds. Once I have paid back, you give my Wallet with my Funds back.
This is not secure.
BitGo only controls one of three private keys associated with addresses where coin is 'stored'. Two keys are required spend the coin.
The customer's "primary" key is designed to initiate all transactions. The customer will sign transactions with this key, and provide the signed transaction to BitGo, who will then verify the requestor is authorized to request that BitGo sign the transaction based on account settings. If all requirements are met, BitGo will sign the transaction. There is a 3rd key, held by the customer, designed to be a "cold storage" key, that can be used in conjunction with the "primary" key to spend any coin within the address.
The above means, that the lender will be unable to spend any coin within the wallet, and the OP would be able to move any coin held in the BitGo wallet.