Your point is valid, maximizing Bitcoin allocation early can accelerate long term gains, but it is also a higher risk approach. The challenge is that without a decent emergency fund, unexpected expenses could force you to sell Bitcoin at an unfavourable price, effectively turning a temporary dip into a real loss.
It's impossible for you to have a decent emergency funds in the beginning of your bitcoin accumulation phase because you need up to a year or two to be able to build up an emergency funds of three months of your income. This is the main reason why it's important to build your emergency funds with the same amount that you are using to DCA for a start til you have built up your emergency funds.
Emergency may come or not, therefore allocating more money to your emergency funds and allow your bitcoin investmet to be two times smaller than your bitcoin investment is wrong because of debasement of fiat currency overtime.
Of course, it is important to know when one has an emergency before saving Bitcoin. This should be at least 6-7 months of his necessary expenses in the emergency fund. Yes, you are right, he can save some amount of Bitcoin every month until he accumulates his emergency fund. Which he will gradually accumulate his emergency fund and start saving Bitcoin with it.
There is no guarantee that an emergency will not come, when he invests some amount of money in Bitcoin, if at that time he needs money in an emergency, he can spend the money in his emergency fund, which will not put any pressure on his Bitcoin investment.
People can face emergencies at any time. No one knows exactly when it will happen, which is why being prepared in advance is definitely a good idea, especially for those who are interested in long-term investment in Bitcoin. If a reserve fund can be formed for a period of 3 months, it is definitely a good idea. There is no need for him to take extra time to form his reserve fund. If he forms a part of his discretionary income for the reserve fund and continues to invest in Bitcoin regularly with the other part, then he can increase the amount of Bitcoin at the same time and ensure his financial security in the long term. Profit cannot be guaranteed in investing in Bitcoin, but the possibility increases if you keep it for a long time.