Hypersonic refers to Mach5 and above if you're talking to anyone in aviation. I don't think I've ever run across an alternative definition.
I'm not sure why you're talking about head- or tail-winds when we are discussing speeds in the several thousand miles per hour range.
As for the project, you could fund it (or pre-fund it) completely in the black for a variety of reasons. For example, if you thought the project was
vital, and the next administration was likely to kill it.
Alternatively, you might fund an existing SAP on a shoe string or place it on life-support giving it just enough funding to keep the heart beating,
but not enough to really proceed forward in the hopes of reviving it later in happier times or when it might be deemed vital.
Or you could just cut it.
I won't pretend to know which happened here, but I'm inclined to think that we're too close to the finish line with too much invested to kill it
outright. But Waynos may be right, it may be sentimentality clouding my judgement.