I disagree. It is an entirely normal expectation in politics that if any senior member of the Administration, up to and including the Vice President, has a disagreement with the President on a matter of policy that they are unwilling to compromise on, it is their duty to quietly resign. The "price" of being a senior member of the Administration is that you have a hand in policy, but once a decision has been made, it's your job to set aside your disagreement and back it to the best of your abilities, or resign if you feel you cannot do so in good faith.
Biden's saying he would have resigned if he had such a fundamental disagreement with President Obama while being Vice President, and he expects Harris to do the same, because she's Vice President and not President.