It's not uncommon that they would drink it "green". Although they lose the advantage of the small beer by not boiling it, but maybe that was what we call today a "given" ???
I have seen reports where in Canada, British troops started drinking the spruce beer immediately after it went into the barrel, and it started top fermentation as they were drawing it by tap from the bottom over the following week. That was molasses based too.
OH and don't bother trying spruce beer, military fashion...it's tasty when it's aged a year, but military fashion it tastes like a 50/50 mix of Diet Pepsi and original flavor Listerine mouthwash. It did keep away scurvy in winter though....
So much of what we think of as "beer" today is derived from the German beer traditions that it is sometimes difficult to imagine what beer back then was like.
Another thing to consider is that this recipe is for "Small Beer", fit for man, woman and child. So, flat molasses water might be on par.