I generally agree, though I have some issues with parts of the biological analogy. I believe there are two different meanings of "software" conflated here.
If we look at software as a social phenomenon, then all the constraints you mention apply. However, if we look at software just as an executable artifact - it does not decay. Bit rot isn't real. Hardware can break down, but bits don't magically flip out of order just because the original developer went AWOL. This is important, because there seems to be this notion in our industry that everything needs to be updated and updatable all the time. But the truth is, unless someone purposefully screw it up (time-limited software, or Internet dependency), I can boot up my old machine and still do real work with decade+ old software.
If we look at software as a social phenomenon, then all the constraints you mention apply. However, if we look at software just as an executable artifact - it does not decay. Bit rot isn't real. Hardware can break down, but bits don't magically flip out of order just because the original developer went AWOL. This is important, because there seems to be this notion in our industry that everything needs to be updated and updatable all the time. But the truth is, unless someone purposefully screw it up (time-limited software, or Internet dependency), I can boot up my old machine and still do real work with decade+ old software.