Let's just say, for the sake of argument, that someone had decided
(all safety concerns duly noted) that they were never, ever going to
use the blade guard/splitter assembly that came with their table saw.
Wouldn't it be possible to take the splitter, and with a little
creative work with an angle grinder, reduce it to something resembling
a riving knife?

Of course this would depend upon the mounting setup of the particular
saw, but so long as the front part of the splitter mounted securely to
the saw, this should work, right?