This gets a little difficult, in that it seems to define "humanism" as a religion. But I see this is as more the peculiarities of the English language. In this case, there are certain privileges given to groupings of service members, such as making available personal counselors (in their language "chaplains") and allowing group gatherings, which it calls "religion," primarily because it hasn't thought of another, better word. So while secular humanism is not, per se, a "religion," I would say that it falls well into the practical intent.
Military chaplains are trained to offer certain services across different, often incompatible, religions, so already you have a stretching of the word. They are also trained to re-frame varying theologies into the language of other denominations or religions when talking to soldiers of different faiths. Some are better at this than others. I read recently that some Fundamentalist chaplains balk at taking this kid of training. Presbyterians, on the other hand, usually have no issue here.
As noted earlier, unless I misunderstand Spinoza, he would say that "Science says" and "God says" are basically just two variants of the same statement, which is why Einstein was comfortable talking about relativity and God in the same breath. Einstein was defining the basic laws of "God" as accurately as possible. A Fundamentalist would not be happy with that, but Einstein seemed fine with it.