We must all understand that investment using the DCA strategy is normally a flexible form of investment, normally meant to be done with not really a specific amount but inview of capital at hand for investment doing it atonce and topping or withdrawing (either a little percentage at or higher percentage and even total) could be done.
However, considering bitcoin investment as a long-term investment with ups and downs without neglecting the volatility, the DCA strategy was brought up to give flexibility in investment either your capital. Is high or low does not matter so fat you are going to be holding for a long and with this higher capital could be invested on an interval basis giving the advantage to balance the investment in terms of its ups and downs ( this can only be achieved over a long period).

Now having a steady inflow or not should not affect your emergency fund, although having a steady inflow is good advice what about those who want to invest but have no steady inflow....
There's only one way for them to secure their emergency fund which is still the DCA strategy  but it could be done in a way to break  out of investment into emergency  
For example
If I'm used to investing $300(taking correction) a week and this left me with little emergency funds then I could set a week or two out of a month for my emergency, during those two weeks I could cut $200 into my emergency fund instead of adding all to my stash...
Thus if there are enough emergency funds then I could divert it all into my accusations during these Emergency Week.
This strategy should also work with x>300 even below hundred