Emergency funds are needed to protect your Bitcoin holdings from any danger, whenever you use an emergency fund, you can immediately plan your investments according to the right plan and make your investments long-term. There are many Bitcoin holders who do not use emergency funds, they face the danger of taking their Bitcoins to their destination according to the plan.
And maybe after a while they have to sell their Bitcoin holdings and face different situations. Make investments that you can use for a long time according to the plan, that is why it is of course most important to have an emergency fund.
Emergency fund has its main role is protecting your life and well-being. I agree that if you have good individual financial management including your spending fund, emergency fund and investment fund, you will less likely have to touch your investment fund because you need money and only can get it from your investment fund.
However the main purpose of emergency fund is not defending your investment capital, it's like a consequence of good financial management from which you can have better management for both your spending fund, emergency fund and investment fund.