My guess - is first priority is “Manage the securities portfolio to balance overall asset risk exposures with liabilities”. main task for the bank is ALM.
You’re 110% right about needing liquidity, but I’d be careful about answering an essay question saying banks don’t provide liquidity. I think I know what you mean b/c he was talking about investment portfolios, but a major part of a bank’s loan portfolio is collateral based lending, or providing funds/liquidity to clients based on values of less liquid assets. An economy is in big trouble if banks aren’t providing liquidity. The credit crisis of 2007-2009 was largely based on banks not providing liquidity to the economy that needed it, which largely was a function of them not having liquidity as you correctly mentioned.